Use a common format for all include guards, make sure each header file
has one and make sure it's named after the file name.
And as a random extra in this commit: Make sure the gen_version.h file
generated by cmake ends with a line break.
Closes#59.
Use Qt Designer for the create index dialog.
Change the layout of the create index dialog completely to be easier to
use and more powerful.
Rewrite most of the index creation code to be easier to understand and
more flexible.
