3.6.0 (stable)

* sigc++config.h.*: Update and clean up a bit for Visual Studio
  (Chun-wei Fan) Pull request #95
* scoped_connection: New wrapper to auto-disconnect a slot
  Issue #87, pull request #97 (Daniel Boles)
* signal: Add connect_first()
  (Kjell Ahlstedt) Issue #81 (LordVolumeForm)

Documentation:
* connection: Improve the class documentation
  (Kjell Ahlstedt) Issue #88 (Daniel Boles)
* Improve Visual Studio build documentation
  (Chun-wei Fan) Pull request #93
* Remove AUTHORS and add general information to README.md
  (Kjell Ahlstedt) Issue gtkmm#140
* manual: Add paragraph about new scoped_connection
  Pull request #99 (Daniel Boles)

Tests:
* Add test_scoped_connection
  Pull request #97 (Daniel Boles)

Build:
* Meson: Don't copy files with configure_file()
  (Kjell Ahlstedt)
* Meson: Fix the evaluation of is_git_build on Windows
  (Kjell Ahlstedt) Issue gtkmm#131 (William Roy)
* CMake: Prevent multiple target declaration for uninstall
  (Francesco Emanuele D'Agostino) Pull request #85
* Visual Studio: Support static builds
  Issue #90 (Swat-SomeBug)
  (Chun-wei Fan) Pull request #91
* Meson: Don't require the 'dot' command to build the documentation
  (Kjell Ahlstedt) Issue #98