* finish conversion to native Qt4 classes

	Most forms still use classes from Qt3Support module which has been
	dropped in Qt5. Most of the time the migration is simple but still
	tedious enough. The ultimate goal is allow twinkle to be built against
	either of Qt4 and Qt5.

* make KDE support work again

	After cleaning up the autotools config, twinkle only builds with
	--without-kde. This is only temporary, the goal is to allow building
	against KDE4 libraries (and, preferrably, also KDE5).

* IPv6 support

	Still missing, AFAIK.

* t_gui locking

	Dirty workaround for (mostly) calling GUI related methods from non-GUI
	threads. Doesn't actually work with Qt4, causing segfaults. Analyze
	the remaining uses and get rid off it.

* MEMMAN_* tracking macros

	Ugly and unreliable (too easy to forget adding them). Either replace
	them with overloaded new and delete operators or kill them completely
	and rely on valgrind.