This commit is a big rework of the FontLoader/FontMetrics interaction. Only Qt4 for...

This commit is a big rework of the FontLoader/FontMetrics interaction. Only Qt4 for now, I would be grateful is somebody steps up for qt3 and gtk.

Basically, I replaced all methods in the font_metrics namespace by a proper virtual interface FontMetrics. The FontLoader is _the_ container for FontMetrics.

This patch should also bring some optimizations in a number of place in the code. This is because we do not need any more to search for the LyXFont at each font_metrics call. In effect, the speed advantage is not as sensible and this is a bit deceiving considering that this was my primary motivation behind the patch. But I like the patch anyway as it cleans up the relation and interfacing between fonts, metrics and frontends.

* frontends/FontMetrics.h: new virtual interface. Renamed from font_metrics.h

* qt4/GuiFontMetrics: corresponding qt4 implememtation. Renamed from qfont_metrics.C. The smallCaps particular case treatment has been transfered here as well as the width cache for MacOSX and Windows.

* qt4/QLPainter.C: the smallCapsText has been reworked to return the width of the drawn text.C

all other files: replace font_metric helper function call with corresponding FontMetrics method calls.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@15265 a592a061-630c-0410-9148-cb99ea01b6c8