Issue 3286: add single-C time signature style

Issue 3286: add single-C time signature style

This style is identical to single-digit except that C is printed
instead of 4 and cut-C is printed instead of 2.

[Dan Eble, 2014-10-26 03:33:51]

fix regtest texidoc

[benko.pal, 2014-10-26 07:40:58]

I think we don't want 4/8 displayed as C by default, neither 2/4 as cut C.
(I also feel uncomfortable to enter \time 2/1 for the Bach Kyrie or Gratias.)

[Dan Eble, 2014-10-26 17:24:01]

On 2014/10/26 07:40:58, benko.pal wrote:
> I think we don't want 4/8 displayed as C by default

Then this change should not bother you because this new style is not the
default.

> (I also feel uncomfortable to enter \time 2/1 for the Bach Kyrie or Gratias.)

I'm sorry about that.  Moving from emotion to reason, is there any practical
difference?  An advantage of this style is that it is easy to name and describe,
in contrast to a style which is like the default with one exception.

[benko.pal, 2014-10-26 20:20:50]

On 2014/10/26 17:24:01, Dan Eble wrote:
> On 2014/10/26 07:40:58, benko.pal wrote:
> > I think we don't want 4/8 displayed as C by default
> 
> Then this change should not bother you because this new style is not the
> default.

ah, indeed, sorry for the noise.