Documentation now expects autogenerated configuration variable documenation at Documentation/NuttXConfigVariables.html

Add a tool to auto-generated documentation of NuttX configuration variables (still a work in progress)

Fix comments, references to the old SVN, and links to the old SVN.  Replace with equivalent GIT info

Fix major misthink in Cortex-M0 port:  The Cortex-M0 has no BASEPRI register.  We have to revert to using the nasty PRIMASK register