Include guards need to be unique within GParted code and all included
library header files.
http://en.wikipedia.org/wiki/Include_guard#Difficulties
Use this model for all include guards:
#ifndef GPARTED_FILE_NAME_H
#define GPARTED_FILE_NAME_H
...
#endif /* GPARTED_FILE_NAME_H */
Closes Bug #539297 - Make include guards unique
Some classes contained private attributes which were used only by a single
member function. Such items were moved to the corresponding function implementations
to stress their limited usage scope.
A few unused variables were also deleted.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>