Thune - Major improvement to the handling of local function values.
Locals can now be passed to inner functions and caught when returned.
Functions are no longer tied to the thread which created them.
The localArgBlk has been eliminated and locals are now stored on the stack.
To accomodate this, the data stack is now separate from the control stack
and grows upwards. This also means that functions can no longer access the
stack below the function call. A limit of one returned value is in place.
To regain full stack usage, locals could be stored on the control stack.
The only downside would be an extra copy of arguments from the data to
the control stack.
ur_wordCell() is now a function rather than a macro.
uc_do() has been merged into ur_eval() and 'do is now implemented as an opcode.
. & .s now use uc_console_out() rather than dprint.
