Allow non-whitespace to separate numbers in realdice input

[ulif]

Current input of dice rolls with the realdice randomness-source expects whitespace characters to separate numbers. With reguiar expressions we could allow also colons, dots, or other (non-digit) chars.

For instance, instead of 1 2 3<CR>2 3 1<CR> we could accept 1, 2, 3<CR>2-3-1<CR> and similar input.

This change was brought up by @alanhoyle in #58 based on recent changes from @adinklotz .

[alanhoyle]

I've started following the developer install instructions and will hopefully submit a pull request soon.