patch #4686: Add support for USBasp, a simple USB programmer
* usbasp.c: New file, implement the USBasp driver.
* usbasp.h: New file, interface declarations for USBasp.
* Makefile.am: Wire the new files into the build.
* avrdude.conf.in: Add the usbasp programmer entry.
* config_gram.y: Add the usbasp token.
* lexer.l: (Ditto.)
* avrdude.1: Document the USBasp programmer.
* doc/avrdude.texi: (Ditto.)
git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@656 81a1dc3b-b13d-400b-aceb-764788c761c2
joerg_wunsch