'_val' <=> '' in gmpf.c
Adding a precision type check in GMP::F MPFR functions like #sqrt
Document 4 more MPFR methods
Reorganizing GMP::F#** a bit, and adding first tests for GMP::F#**
Cleaning up some TODOs in GMP::F#**
Adding comments for rounding mode constants
Merge branch 'master' of github.com:srawlins/gmp

Conflicts:
	ext/mprnd.c
adding the 'rake yard' task