Real fix for bug 1395 by Stefan Schimanski, this commit replace the one done at revis...

Real fix for bug 1395 by Stefan Schimanski, this commit replace the one done at revision 17836 which was reverted!

Locking counter added to MacroData: it is increased before drawing/
metric calculations and decreased afterwards in InsetMathMacro. If a
macro is already locked at that point, "Self reference: \foo" is
drawn instead of the macro definition to avoid endless loops.
Moreover inside of the arguments of the macro the counter is
temporarily decreased as those cases do not cause loops. (fixes bug
#1395)

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@17841 a592a061-630c-0410-9148-cb99ea01b6c8