Source-inspector

------

- Add support to collect strings, comments and symbols from source using Pygments
- Add support to collect strings and symbols from source using tree-sitter

------

Improve xgettext handlings.
- Handle empty, whitespace and special characters. https://github.com/nexB/source-inspector/issues/11
- Properly handle the multiple starting lines for a string. https://github.com/nexB/source-inspector/issues/13
- Run xgettext with UTF-8 encoding. https://github.com/nexB/source-inspector/issues/14

------

Add source strings collection using xgettext.
Ignore anonymous symbols in symbols_ctags.
Fix typo in package name.
Rename symbols output to source_symbols.

------

Initial release with basic source symbols collection using Universal Ctags.

Also available as ScanCode Toolkit plugin.