Changes to 0.7.3

* Update to mpfr 2.1.1
* Documentation update, document the plotting functions for example.
* Blinking cursor can now be turned off in gnome-genius
* Set default precision to 128 bits.  Who needs 256 can set it in the
  preferences.  Also save/restore the precision
* Add LinePlotClear, LinePlotDrawLine functions to allow drawing arbitrary
  lines and to allow a way to do parametric plots until that functionality
  is actually added
* Added: NewtonsMethodPoly, wait
* Lots of work on the internal number structure to make it faster/more
  memory efficient and to fix some possible bugs/issues
* Fix float formatting bug that sometimes caused hangs and crashes
* Fix large leak on element by element operations
* Fix compilation with external mpfr
* Bunch of other little bugs/issues fixed.