Changed the object file and library format. There is now an additional

Changed the object file and library format. There is now an additional
string table in the object file that (currently) holds all identifiers
from the import, export and debug info sections. The plan is to put all
strings into this table, so we have them in a central place and don't
waste memory. Apart from that, the indices are unique, so comparing strings
should be a lot easier than before (as soon as the programs take advantage
of this fact, which is currently not the case).

git-svn-id: svn://svn.cc65.org/cc65/trunk@2169 b7a2c559-68d2-44c3-8de9-860c34a00d81