Latexmk

[aartoni]

Removes texclear and simplifies compiler by using latexmk. Compared to the previous version, this latexmk configuration:

• sets the default format to XeLaTeX ($pdf_mode = 5);
• compiles in silent mode; errors can still be found in the log file;
• autodetects Biber/BibTeX, using Biber for BibLaTeX;
• calls Biber/BibTeX only if the bib files exist, reducing compiler calls by one;
• outputs all compiled artifacts to out, simply add that to your .gitignore instead of listing numerous files;
• simplifies configuration overwriting by honoring the .latexmkrc file from the root of any LaTeX project; VimLeave and compile will read those.
• Automatically detects compiled artifacts to delete during cleanup, thanks to $cleanup_includes_cusdep_generated and $cleanup_includes_generated (goodbye texclear).

[aartoni]

This PR had already been pushed before (#1428), however I've mistakenly closed it by deleting the branch on my fork of LARBS. Anyway, this one has an improved description.