Figure.meca: Add aliases for C, E, G, and W

[yvonnefroehlich]

Description of proposed changes
This PR aims to add aliases for pygmt.Figure.meca:

• add aliases
  • C -> cmap
  • E -> extensionfill
  • G -> compressionfill
  • W -> pen
• [ ] add unit test

Related to comments #2329 (comment), #2329 (comment), and #2329 (comment).

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.
• Use underscores (not hyphens) in names of Python files and directories.

Slash Commands

You can write slash commands (/command) in the first line of a comment to perform
specific operations. Supported slash commands are:

• /format: automatically format and lint the code
• /test-gmt-dev: run full tests on the latest GMT development version

[seisman]

@yvonnefroehlich Is this PR finished? I don't think a unit test is necessary, because this PR only adds aliases, and we're confident that aliases work.

[seisman]

BTW, could you please split this PR into two separate PRs: one for the docstring changes and another one for the new aliases.

[yvonnefroehlich]

BTW, could you please split this PR into two separate PRs: one for the docstring changes and another one for the new aliases.

I submitted a separate PR #2360 for the docstring changes.

@yvonnefroehlich Is this PR finished?

Yes, this PR should be finished.
But I think, I like to add also aliases for W -> pen and C -> cmap. But I can do this in a separate PR 🙂.

I don't think a unit test is necessary, because this PR only adds aliases, and we're confident that aliases work.

This is fine with me, but I have experience with testing code... Adding a unit test was suggested in #2345 (comment).

[seisman]

Yes, this PR should be finished.
But I think, I like to add also aliases for W -> pen and C -> cmap. But I can do this in a separate PR .

It depends on you. You can keep working in this PR if you want to add more aliases.