Create parameter for maximum number of template instantiations.

Currently, the maximum number is hard coded. This PR creates a command line parameter for it.
Requested by bearophile: http://forum.dlang.org/post/tsphogrgyjeqyeadqkds@forum.dlang.org
Remove deprecated pragmas.

This was advertized in news group.
Merge pull request #663 from redstar/deprecated

Remove deprecated pragmas.
More cleanup of pragma.cpp

Replace matchPragma() function by a simple comparison.
Merge pull request #661 from redstar/nested

Create parameter for maximum number of template instantiations.
Add line number to error message of -nogc switch.

This was suggested by bearophile in the news group.
It also changes all Loc objects to be passed by reference.