This fixes cppcheck warnings (style) 'class x' does not have a copy constructor
which is recommended since the class contains a pointer to allocated memory.
* remove unused class TexStream.
* remove unused virtual method Inset::cellXOffset
* remove second argument of FileDialog constructor, which was actually
not used
* remove some dead local code
* remove some unused private members of classes
* in InsetMathNest::updateBuffer, fix the logic of a test
avoids a useless object creation, as Qt tolerates the
pointer to be null as well.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@39863 a592a061-630c-0410-9148-cb99ea01b6c8
