parser.yy: allow "scalar" to be a negative literal number

This makes the syntax of the value for \override (a hardwired syntax construct which accepts a "scalar") and \tweak (which is a music function accepting an expression of type "scheme?" possibly ending up as a negative number) more comparable.

http://codereview.appspot.com/13270048

Patchy the autobot says: passes tests.

Sheesh! You dudes don't leave much for the Bug Squad, do you? I didn't even get a chance to research it, much less decide if there really was a bug.

Nive work, David!

You dudes don't leave much for the Bug Squad, do you?

A lot, actually. In this case, it was more like a can of worms than a bug. It was easier to get rid of it (or at least its more troubling aspects) rather than categorize it...

Patch on Countdown for September 6th - 06:00 GMT

Patch counted down - please push

Pushed to staging as commit c7320b8c6dd5ef813602526c340a3e30c2cc91f7 Author: David Kastrup Date: Sat Aug 31 18:57:09 2013 +0200

Issue 3527: parser.yy: allow "scalar" to be a negative literal number

This makes the syntax of the value for \override (a hardwired syntax
construct which accepts a "scalar") and \tweak (which is a music
function accepting an expression of type "scheme?" possibly ending up
as a negative number) more comparable.