Merge branch 'docs/#36_code_guide' into 'devel'

Code guidelines

See merge request !5

GUIDELINES.md

+# Coding Guide
+
+Here lies all the guidelines regarding the code development for **dccQuantities**.
+
+- [Python Style Guide](#python-style-guide)
+- [Development workflow](#development-workflow)
+
+---
+## Python Style Guide
+
+**dccQuantities** follows the [Google Python Style Guide](https://google.github.io/styleguide/pyguide.html) excepting the following deviations.
+
+### 2 Python Language Rules
+#### 2.1 Lint
+
+Instead of `pylint`, run `ruff` over your code with the set of rules defined at `ruff.toml`.
+This change is decided as `pylint` is quite slower, as well as `ruff` not only allows defining more rules but also formating the code.
+
+**Lint suppression**: No warning should be suppressed, unless there is a valid and discussed reason to do so.
+If any warning requires to be suppressed, a revision of the `ruff.toml` configuration might be required.
+
+### 3 Python Style Rules
+#### 3.2 Line length
+
+Maximum line length is _120 characters_.
+
+The exceptions to this rule are the ones defined at the original guidelines.
+
+#### 3.3 Parentheses
+
+Avoid using parenthesis for redundant packing/unpacking.
+
+**Yes:**
+```python
+for ham, spam in iterable:
+    ...
+
+return foo, bar
+```
+**No:**
+```python
+for (ham, spam) in iterable:
+    ...
+
+return (foo, bar)
+```
+
+#### 3.8 Comments and Docstrings
+##### 3.8.1 Docstrings
+
+All docstrings should follow the [NumPyDocs conventions](https://numpydoc.readthedocs.io/en/latest/format.html), with the same line length as the one defined for the general code.
+
+ A docstring should be organized as a summary line (one physical line not exceeding 80 characters) terminated by a period, question mark, or exclamation point.
+ When writing more (encouraged), this must be followed by a blank line, followed by the rest of the docstring starting at the same cursor position as the first quote of the first line.
+
+---
+## Development workflow
+
+All changes must pass a review process through a pull-request.
+The general guidelines for this process are defined at [`CONTRIBUTING.md`](CONTRIBUTING.md).
+
+### General changes
+
+It is defined as "general changes" those that can be labelled with the tag `feature/`, `bugfix/` or `docs/`.
+The branches for these changes are created **from 'devel'** and **_squash merged_ into 'devel'**.
+
+![general_pull_request](doc/imgs/general_pr.png)
+
+After merging, other branches also created from 'devel' should be updated by **rebasing onto 'devel'**. 
+
+### Hotfixes
+
+A **hotfix** correlates to code changes that must be integrated immediately at the latest release, with no window to wait to be resolved with the unreleased changes.
+The branches for these changes are created **from 'main'** and **_squash merged_ into 'main'**.
+
+> Note: Hotfixes must update the PATCH number at the version within the pull request.
+ 
+![hotfix_pull_request](doc/imgs/hotfix_pr.png)
+
+After merging, the branch 'devel' should be updated by **rebasing onto 'main'**.
+
+### Releases
+
+**Release branches** put together all unreleased changes to be included into the 'main' branch.
+A release branch should contain only a 'bump version' commit, and it must be created **from the latest 'devel'** and **_merged_ into 'main'**.
+
+![release_pull_request](doc/imgs/release_pr.png)
+
+After merging, the branch 'main' should be **merged into 'devel'**.

ruff.toml

+# Enforcing line length greater than 88:
+line-length = 120
+# Ruff report as a concise list of all issues:
+output-format = "concise"
+
+[format]
+docstring-code-format = true
+skip-magic-trailing-comma = true
+
+[lint]
+select = [
+    "A",    # flake8-builtins
+    "ANN",  # flake8-annotations
+    "ARG",  # flake8-unused-arguments
+    "B",    # flake8-bugbear
+    "BLE",  # flake8-blind-except
+    "C4",   # flake8-comprehensions
+    "D",    # pydocstyle
+    "DOC",  # pydoclint
+    "E",    # pycodestyle error
+    "F",    # Pyflakes
+    "FA",   # flake8-future-annotations
+    "I",    # isort
+    "ICN",  # flake8-import-conventions
+    "ISC",  # flake8-implicit-str-concat
+    "N",    # pep8-naming
+    "NPY",  # NumPy-specific rules
+    "PD",   # pandas-vet
+    "PIE",  # flake8-pie
+    "PL",   # pylint
+    "PT",   # flake8-pytest
+    "RET",  # flake8-return
+    "RUF",  # Ruff-specific rules
+    "SIM",  # flake8-simplify
+    "TC",   # flake8-type-checking
+    "W",    # pycodestyle warning
+]
+ignore = [
+    "ANN002",   # missing type for *args
+    "ANN003",   # missing type for **kwargs
+    "D401",     # first line in docstring as imperative mood
+    "PLR6301",  # no-self-use
+    "PLR0913",  # too-many-arguments
+    "PLR0904",  # too-many-public-methods
+    "PLR0916",  # too-many-boolean-expressions
+    "PLR0912",  # too-many-branches
+    "PLR0904",  # too-many-public-methods
+    "PLR0911",  # too-many-return-statements
+    "PLR0915",  # too-many-statements
+]
+preview = true
+
+[lint.flake8-annotations]
+allow-star-arg-any = true
+mypy-init-return = true
+suppress-none-returning = true
+
+[lint.flake8-unused-arguments]
+ignore-variadic-names = true
+
+[lint.isort]
+split-on-trailing-comma=false
+
+[lint.pycodestyle]
+ignore-overlong-task-comments = true
+
+[lint.pydocstyle]
+convention = "numpy"
+
+[lint.pylint]
+max-args = 10