-places/-precision will do.

-places controls the length before the radix, while -precision does so
for the length after the radix. So we don't need -places1 and -places2
(which are awful names anyway).
Switch on type.

And the end of the constructor, switch on type just before the
construction of the final pattern.
Merge branch 'master' of github.com:Abigail/Regexp-Common510-Number
First tests for decimal patterns.