Improve regexes

[liviuconcioiu]

Far from complete, but I've replaced those:

[\d\.]       => [\d.]
[\.\d]       => [.\d]
[a-z0-9_\-]  => [a-z0-9_-]
[a-z0-9\-]   => [a-z0-9-]
[a-z0-9_ \-] => [a-z0-9_ -]
[ _\-]       => [ _-]
[\.0-9]      => [.0-9]
[0-9\.]      => [0-9.]
[ \-]        => [ -]
[_ \-]       => [_ -]
[_\.]        => [_.]
[_ \.]       => [_ .]
[ _\-\.]     => [ _.-]

#7640 (comment)