- Create a common subpackage for architecture-independent files
required by both cli and gui applications.

- Update to version 4.2:
* Added support for Critic markup (gl#saalen/highlight#197).
* Added support for jam/ham (gl#saalen/highlight#196).
* Added support for PureScript.
* Added support for Nix (gl#saalen/highlight#200).
* Added ino file mapping / Arduino C (gl#saalen/highlight#201).
* Fixed RTF page color attributes (gl#saalen/highlight#195).
* Fixed identifier parsing in yaml.lang (gl#saalen/highlight#190).
* Fixed symbol parsing in lisp.lang (gl#saalen/highlight#198).
* Fixed string parsing in csharp.lang (gl#saalen/highlight#199).
* Fixed string parsing in conf.lang (gl#saalen/highlight#203).
* Added make target `install-lib-shared` to install shared lib
(gl#saalen/highlight#202).
* GUI: Added Japanese translation.
* GUI: Disabled floating panel (state restore fails).
- Remove useless dependency of gui on cli.