Yacky Yacc

I'd hopped I would get by without having to learn the mysteries of Bison and how to build parsers. Unfortunately parsecvs uses it to grok the CVS files. Someone has added some new binary files into the CVS tree and it's causing parsecvs to go into a death spiral of memory allocation. The backtrace shows yyparse() and yylex() in the call chain so I suppose I'd better learn how this is meant to work before I break it.