Use fractions rather than Scheme pairs for \scaleDuration, timeSignatureFraction et al (issue 6200068)

[k-ohara5a5a]

http://codereview.appspot.com/6200068/diff/2001/Documentation/notation/rhythms.itely
File Documentation/notation/rhythms.itely (right):

http://codereview.appspot.com/6200068/diff/2001/Documentation/notation/rhythms.itely#newcode331
Documentation/notation/rhythms.itely:331: a4*2/3 gis a
Oh yes.  You had asked who were "some people" who use this construction.
 It's not just me this time; I also see it in other people's scores on
mutopiaproject.
I'll admit that I used it to avoid the Lisp syntax in \scaleDurations
#'(2 . 3)

http://codereview.appspot.com/6200068/diff/2001/Documentation/snippets/new/changing-time-signatures-inside-a-polymetric-section-using--scaledurations.ly
File
Documentation/snippets/new/changing-time-signatures-inside-a-polymetric-section-using--scaledurations.ly
(right):

http://codereview.appspot.com/6200068/diff/2001/Documentation/snippets/new/changing-time-signatures-inside-a-polymetric-section-using--scaledurations.ly#newcode25
Documentation/snippets/new/changing-time-signatures-inside-a-polymetric-section-using--scaledurations.ly:25:
\scaleDurations 8/5 {
Somehow, this worked before the patch.  Not a problem, just an
observation.

http://codereview.appspot.com/6200068/diff/2001/lily/lexer.ll
File lily/lexer.ll (right):

http://codereview.appspot.com/6200068/diff/2001/lily/lexer.ll#newcode487
lily/lexer.ll:487: {FRACTION}   {
Stupid question, but I can't figure it out.  Can we remove this pattern
from the rules for individual starting states, now that it is matched
globally ?

http://codereview.appspot.com/6200068/diff/2001/lily/lexer.ll#newcode528
lily/lexer.ll:528: {FRACTION}   {
?

http://codereview.appspot.com/6200068/diff/2001/lily/lexer.ll#newcode573
lily/lexer.ll:573: {FRACTION}   {
?

http://codereview.appspot.com/6200068/