MapServer Layer shouldn't encode "+"

[crschmidt]

URL encoding broke the MapServer layer.

The "+" characters that are sent in the parameters need some kind of protection from encoding, becuase mapserver needs them to not be encoded.

[crschmidt]

Since "," is normally URL encoded, but isn't in lists, we can make the parameters we want to put a "+" in a list. Then, we can replace "," with "+" at the end of the function -- the only literal commas in the output should be the ones that we put in the lists -- and that should do it...

Except in the case where a URL contains a comma itself. Crap. Well, the given patch will work so long as your URL doesn't contain ","s in it.

[crschmidt]

sub-class getFullRequestString to modify parameters for mapserver

[sderle]

applied as r2544.