Fix applying default selection colors after editing 'selection' style

Default colors were not restored when disabling the override flags.
Do not override default selection foreground style
Add workaround for users with an invisible selection style

This is likely to be the case for any users that copied the system
selection style line as this was incorrectly set before, but not
applied.
Adding a small note pointing out that setting a default keybinding might not the best idea for plugin maintainers
Do not suppress warnings (Windows makefiles)

Also do not define G_OS_WIN32.
Fix using CXX, CC as usual to prevent override problems (Windows build)
Update of Spanish translation
Update of Italian translation
Update of Japanese translation
Remove sentence from documentation that doesn't apply anymore

With newer GTK+ releases, leaving this field blank causes the "Recent
Files" "feature" to be used rather the the expected current working
directory. No replacement text added to explain the new behaviour since
it would be incorrect with older GTK+ versions, would likely be incorrect
on Windows with native dialogs and it will possibly be reverted in GTK+
in the future.

Recenerate HTML manual, including previous changes from other commits.
Restore secondary clear icon functionality in Preferences dialog

Ensures all entries that get a clear icon added to the secondary position
also set the secondary icon to be activatable. This was probably
introducted during the Glade switch and could be fixed in the Glade file
but this fix ensures that even hard coded entries will always have their
clear icon activatable.
Always select current editor font when showing the font dialog

Previously, choosing another font and then pressing cancel would keep
the font selected rather than resetting it to the current editor font
because the dialog is not destroyed between showings.
Fix documentation using old directory tagmanager/include
Fix Windows build
Update of Lithuanian, Italian, Dutch and Portugese translation
Merge remote-tracking branch 'origin/master' into tm/tree-refactoring
Don't suppress warnings or define G_OS_WIN32 (Windows build)
Show info message if selection style is invisible, not warning
Parse D functions with various attributes/storage classes

Parse @attributes, pure, nothrow.
Parse return types immutable(T), shared(T), inout(T).
Add incompatibilities to NEWS

Add section outlining incompatibilities in accordance with ML.