Advanced F&R rework:

Advanced F&R rework:
- scopes now handled in FindAndReplaceWidget, while lyxfind.cpp only searches within single buffer
- cursor().result().dispatched() now encodes whether a match was found or not, after LFUN_WORD_FINDADV dispatch
- removed a few unneeded functions
- followed a few cosmetic advices

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@32760 a592a061-630c-0410-9148-cb99ea01b6c8