ppp working, including both callback reg and auto api gen

Rewrote tstringsearch to use ppp.  So stringsearch has a pluggable point which is when a string matches. tstringsearch registers a function to get called there which paints taint labels onto the matched string.

All of the taint code (almost) is now moved into the taint plugin, including the taint processor.
I have written a very small api to the taint library in taint/taint_int.h which works since I was able
to access it from the tstringsearch plugin.  This compiles and works.

Note: this is only half of the ssh-keygen backdoor demo.  The other half involves querying taint
at network out via a hacked-up version of the syscalls plugin.  That also would need to register
callbacks with the taint plugin (which is now also pluggable at least at load and stores).
I decided not to check in that code since Josh is coming up wiht somethign much better.
should have been part of last commit
Merge https://github.com/moyix/panda