**NOTES:**
- PR is not yet merged in upstream repository (https://github.com/SalGnt/Sublime-VimL/pull/12),
but sublime-syntax file is already updated with changes.
- Updated syntax test files are added as well
This fixes#1064
- New themes in `$BAT_CONFIG_DIR/themes` are now loaded *in addition* to
the default themes (they may also override).
- The `Default.tmTheme` symlink is not necessary anymore.
This relates to #172
This changes a few things:
- All syntaxes and themes are now stored (as submodules) under
assets/syntaxes and assets/themes
- The default directories for syntaxes and themes are "syntaxes"
and "themes" (used to be "syntax" and "themes")
- The "bat cache" command can now take a `--source <dir>` and
`--target <dir>` option.
- The cached files have been renamed to "themes.bin" and "syntaxes.bin"