Do some work on language and styling files.
On branch master, changes to be committed:
	modified:   languages/c.xml
	modified:   languages/cplusplus.xml
	modified:   languages/python.xml
	new file:   languages/xml.xml
	modified:   styles/default.xml
Remove XML from the special lexers.
On branch master, changes to be committed:
	modified:   src/syntaxhighlightmanager.cpp
Implement sub-menus for language selector.
On branch master, changes to be committed:
	modified:   src/syntaxhighlightmanager.cpp
	modified:   src/syntaxhighlightmanager.h
Re-implement the lexer manager and fix a few bugs.
On branch master, changes to be committed:
	modified:   config/languages/c.xml
	modified:   config/languages/cplusplus.xml
	modified:   config/languages/octave_matlab.xml
	modified:   config/languages/python.xml
	modified:   config/languages/xml.xml
	modified:   src/leptonlexer.cpp
	modified:   src/leptonlexer.h
	modified:   src/scintillaeditor.cpp
	modified:   src/scintillaeditor.h
	modified:   src/syntaxhighlightmanager.cpp
	modified:   src/syntaxhighlightmanager.h