libbitcoinscript

This does the minimal effort to generate a libbitcoinscript.so which can VerifyScript, though nothing else is exposed.

Build with ./configure --enable-shared=yes and you'll find a libbitcoinscript.so installed (or in src/.libs).

It weighs quite a bit, but it works, so I think its worth merging and then trimming down (and adding features) as we go (Ive already got one or two others ready, but first things first).

Please do not ACK this unless you've verified there are no changes before/after the copy/paste.
I don't mind moving these functions. But not including the .cpp source in the library while you are relying on its header file is fragile - just a refactor may break the library. IMHO, the .h and .cpp should be considered as a unit, and if it it turns out that we want the library to be leaner, then that means that the source code needs to be changed to support that.

I'd prefer to not do any such things, and just get the library in a functioning state with minimal changes. Making it leaner can always be done later.