Ignore multiple spaces between user name and expiry in list commands

[Krinkle]

# Without expiry, fine.
CVNBot14 bl add 71.237.252.43  r=vandalism on en.wikipedia
<•CVNBot14> Added: 71.237.252.43 is on global blacklist, added by Krinkle until 02:38, 27 May 2018 ("vandalism on en.wikipedia")

# With two spaces before "x=", adds it as user name, bug!
CVNBot14 bl add 71.237.252.43  x=7440  r=vandalism on en.wikipedia
 <•CVNBot14> Added: 71.237.252.43  x=7440 is on global blacklist, added by Krinkle until 02:39, 27 May 2018 ("vandalism on en.wikipedia")

# With one space before "x=", works as expected.
<•Krinkle> CVNBot14 bl add 71.237.252.43 x=5000 r=vandalism on en.wikipedia
<•CVNBot14> Updated: 71.237.252.43 is on global blacklist, added by Krinkle until 10:43, 20 November 2018 ("vandalism on en.wikipedia")

# With two spaces before "x=", while bad, worked for "bl add", but fails for "bl del", double bug!
CVNBot14 bl del 71.237.252.43  x=7440
<•CVNBot14> Deleted 71.237.252.43 from global blacklist

This means they can be added, but not removed. Anyway, we should fix it so that multiple spaces are ignored.

The problem is at https://github.com/countervandalism/CVNBot/blob/6c60cd4bd1d0f6d8a67847b91ae7fa89570ee827/src/CVNBot/ListManager.cs#L30

^(?<cmd>add|del|show|test) (?<item>.+?)(?: p=(?<project>\S+?))?(?: x=(?<len>\d{1,4}))?(?: r=(?<reason>.+?))?$            

It only considers x = as expiry if there is no space after its value or if there is exactly one space between its value and r=. Given there were multiple spaces, it was not matched, and instead consumed by the <item> match.