Log Message:
Update to 4.1. From the changelog:

- improved handling of Custom theme attributes (#182)
- fixed wrong color code in edit-kwrite.theme
- added rng file mapping (#129)
- improved Lisp highlighting
- GUI: fixed highlighting options tab title (thanks to Craig)
- renamed `std` style name to `def`
- version and README updates
- removed `extras/web_plugins`
- added user-select default property to HTML line number style
- revised color themes
- added two more keyword styles for default themes
- added Custom theme attributes for Plain TeX, LaTeX, SVG and Pango
- enabled syntax message output with `--ls-syntax-error`
- GUI: enabled syntax error checkbox
- added Custom theme attribute
- enabled inline stylesheets with `--ls-hover`
- added Error and Hover theme properties
- enabled syntax error highlighting with `ls-semantic`
- improved LSP message handling
- added delay LSP parameter
- added LSP semantic token styles to base16 themes
- renamed `str` style name to `sng`
- CLI: enabled `--ls-semantic` option
- GUI: enabled semantic checkbox and a server capability test
- added support for the language server protocol
- added new configuration file lsp.conf
- CLI: added `ls-profile`, `--ls-workspace`,`--ls-hover`
- CLI: deprecated `--start-nested`, `--reformat=user`,
  `--reformat-option`, `--base16`, `--delim-cr`, `--plug-in-read`
- GUI: added LSP configuration tab
- added `--syntax-supported` option