Introduction of fractions exposes uniform vector prototype bug

[Mikael Djurfeldt]

In the silly uniform vector (and array) prototype system, the
canonical prototype for uniform double vectors is (according to the
entry on uniform arrays in the manual) 1/3.

However, since 1/3 is no longer a real, uniform vector creation with
this prototype fails...

I have no good suggestion for what to do about this, but one thing is
certain: We can't suggest people to use 1/3 as prototype for double
arrays (at least now without modifying scm_make_uve).

Note also, that prototypes like 1.0 menas uniform float array...

M

(Who leaves this problem for somebody else to fix.)