Accept counts for python assignments

[urbainvaes]

At the moment, gJ from the beginning of the first line of

a = 1
b = 2
c = 3
d = 4
e = 5
f = 6
g = 7
h = 8

gives

a, b, c, d, e, f, g, h = 1, 2, 3, 4, 5, 6, 7, 8

It would be nice if the mapping gJ would accept a count, to allow joining a given number of lines.

[AndrewRadev]

An interesting idea. It feels like most operations that take a count work on a single line by default, and the count "increases" their effect. In this case, it'd be the opposite, a count would limit their effect area. So it feels wrong to me in that regard, but then I don't use counts much anyway, so who knows.

I've implemented the functionality -- it turns out it's not particularly difficult -- but there's a bit of a rub. The plugin uses a clever setup to use gJ as an override, but, if you give it a count, falls back to the built-in gJ.

Currently, you could use the functionality by setting the mapping yourself:

nmap <silent> gJ <Plug>SplitjoinJoin

But I'll think about what I could do to make it available. Maybe a setting to disable the fancy fallback behaviour...