Update to 3.8.1

Changelog:

News in 3.8.1
-------------
* Improvements to the LaTeX and Perl language specs
* Update to gtk-mac-integration 2.0 API
* More unit tests
* Misc bugfixes
* Updated translations

News in 3.8.0
-------------
* Add Libtool versioning. There was an ABI break during this development
  cycle, because some private functions were accidentally exported. So
  the Libtool's -version-info is bumped from 0:0:0 to 1:0:0. On
  GNU/Linux, this results in a version bump of the soname.
* Updated translations

News in 3.7.92
--------------
* New style id for warnings
* Improvements to the completion code and documentation
* Misc bugfixes
* Updated translations

News in 3.7.91
--------------
* Simplify code for the completion
* Improvements of the Perl, R and Ruby language specs
* Misc bugfixes
* Updated translations

News in 3.7.90
--------------
* Improvements in completion
* Add Modelica language spec
* Misc bugfixes
* Updated translations

News in 3.7.3
-------------
* Deprecate gtk_source_completion_move_window()
* Deprecate gtk_source_completion_info_get_widget()
* Deprecate gtk_source_completion_info_set_widget()
* CompletionInfo: always a natural size
* Simplify internal code for the completion (new CompletionModel)
* Fixes for the style schemes and GtkSourceMark
* Other misc bugfixes
* Updated translations

News in 3.7.2
-------------
* Improved unit tests and code coverage support
* Misc bugfixes
* Updated translations

News in 3.7.1
-------------
* Add Bluespec SystemVerilog syntax highlighter
* Improvements in completion
* Add language spec for IDL
* Lots of fixes in gtk doc
* Misc bugfixes
* Updated translations

(ryoon)