Bug 694025 - GLib drop support for adding interfaces after class_init

Without this Dia crashes at startup with new GLib version and the
DiaGdkRenderer being default. Make a new DiaGdkInteractiveRenderer which
follows the pattern also used for DiaCairoInteraciveRenderer. This should
be functional equivalent to what was there before and should work for all
current GLib versions.

(cherry picked from commit 213bdfe956bf8fe57c86316f68a09408fef1647e)
Fix assumption that table->prop_dialog is always valid

Not sure how I made it crash, but this extra safety measure
should not hurt in any case.
Bug 672190 - Inputs Methods don't work in integrated mode

Connect im-related signals also to the integrated UI canvas