More Grcc fixes

[jodavies]

A couple more for grcc:

These improve the printing of messages from grcc by suppressing MesPrint's automatic linebreaks, and relying on those from the grcc format strings.

Also, add an On/Off parameter to enable grcc's verbose printing. With On GrccVerbose; errors in couplings, for example, will print

*** illegal coupling const : nlegs - 2 + 2*loop: 2*loop = 1
*** Error : illegal value of c-constants

or

*** cannot generate : 2*loop is odd : 2*loop = 3, ctotal=3, nExtern=2
*** Process: illegal input: lp2 = 3
*** Error : Process: illegal input

rather than just the cryptic "illegal input" message.

[coveralls]

coverage: 57.866% (+0.9%) from 57.005%
when pulling ebe385f on jodavies:grcc-fixes-2
into d507fac on form-dev:master.