Add fullscreen to to view menu
Replace more GDK_* with GDK_KEY
Make manual reposition after unfullscreen Windows only
Add /d2Zi+ switch for better debug symbols
Fix messages on networks that have chantypes the same as nick prefixes

Closes #763
First round of using GTK accessor functions

This is the first step to build with GSEAL_ENABLE
setup.c uses a deprecated fontchooser,
chanview-tabs.c didn't like the conversion, and
I am waiting to do some work on xtext.c before
converting it.
Fix warning
Add screenshot to appdata file