warn about missing whitespace

[wilzbach]

(This is part of the Phobos style guide)

e.g. between the assignment there should be exactly one space

auto a = 1;
auto a=1; // yield warning
auto a = 1, b = 2;
auto a=1,b=2; // yield warning

or between other operations:

(1 < 2)
(1<2) // yield warning

same goes for operators like for, foreach, if and while

foreach (a;as)
foreach(a;as) // yield warning