GXemul Code2

Moving RELEASE.html to doc/.

Merging in more of the main GXemul and UnitTest classes from the previous experimental C++ branch; updating the configure script to match this.

Moving in src/*.c into src/old_core/.

Minor updates to the TODO.

Speeding up the mvme88k install script somewhat.

Do not check rx interrupts too often, for performance.

Minor cleanup of dev_clmpcc interrupt handling.

Spelling mistake fix.

Attempting to reduce the "first-person"-ness of some parts of the documentation; adding a Thanks section to the intro.html page, where larger code contributions from others can be credited. (None yet.)

Preparing for a 0.4.7.1 release.