Mandatory Cairo use

Cherry-picked from sortsmill Sep 2012.
No BIGICONS

(cherry-picked from ec87736868b6b9db31751139a9e306c65230551a)
Writing a passed pointer as an array doesn’t change its sizeof.

Cherry-pick from sortsmill 2012-09-15
Some char sign casts.

Cherry-pick from sortsmill 2012-09-15
Temporary fix for kerning class dialog with Cairo

For some reason _GXCDraw_CopyArea() causes the glyphs not to be shown in
the kerning class dialog, but no problem with XCopyArea, so just disable
using _GXCDraw_CopyArea() until we figure this out.
Drop code to globally enable/disable Cairo

Cherry-pick from sortsmill 2012-09-17
Conflicts:
	fontforge/prefs.c
	fontforge/startui.c
	gdraw/gxcdraw.c
Drop GDrawCreatePixmap() hack

Cairo is alwyas on now.

Cherry-pick from sortsmill 2012-09-17
Conflicts:
	gdraw/gxdraw.c
Always use cairo

Cherry-pick from sortsmill 2012-09-17
Won't compile due to conflicting change from official
fontforge. Handle later.
Conflicts:
	gdraw/gdrawP.h
	gdraw/gxcdraw.c
	gdraw/gxdraw.c
Drop GDrawCopyScreenToImage()

Not used anywhere.

Cherry-pick from sortsmill 2012-09-17
Conflicts:
	gdraw/gimagexdraw.c
We no longer use Xft

It was used by Pango-without-Cairo path, which is now gone.

Cherry-pick from sortsmill 2012-09-17
Conflicts:
	gdraw/gxdrawP.h
	m4/fontforge_create_pkg-config_files.m4
wam_nocairo no longer used
Drop GDrawHasCairo + some unused code as a result

Cherry-pick from sortsmill 2012-09-18
Conflicts:
	fontforge/charview.c
	fontforge/fontview.c
Drop "Insert Character" dialog

No one even knows it exists, it does not seem to work (with me at least)
and people should use an input method or an external character map if
they really need to.

Cherry-pick from sortsmill 2012-09-18
Conflicts:
	fontforge/fontview.c
	fontforge/startui.c
	gdraw/Makefile.am
	gdraw/descrip.mms
	gdraw/gchardlg.c
	inc/gwidget.h
Drop code for minimum distance hinting

Minimum distance hinting is long gone (since 2005), remove remaining
related code.

Cherry-pick from sortsmill 2012-09-18
Conflicts:
	fontforge/charview.c
	fontforge/cvaddpoints.c
	fontforge/cvgetinfo.c
	fontforge/cvhints.c
	fontforge/cvstroke.c
	fontforge/fontview.c
	fontforge/metricsview.c
	fontforge/nonlineartransui.c
	fontforge/search.c
	fontforge/sfd.c
	fontforge/splineutil.c
	gtkui/viewsgtk.h
	htdocs/xres.html
Drop GDrawDrawArrow

Was only used by the now removed minimum distance hinting code.
Drop XCopyPlane usage

Whatever it does, we don't seem to miss it.
Some comments
Unnecessary include

Cherry-pick from sortsmill 2012-09-19
Conflicts:
	gdraw/gxdrawP.h
Fix remaining usecairo removal due to FF upstream additions
Implement GXDrawDrawArc using Cairo

Cherry-pick from sortsmill 2012-09-19
Conflicts:
	gdraw/gxdraw.c