Description:
------------
I looked myself and determined that the RFC3986 is very spongelike. Compared with other programming languages I noticed that everyone differently converts the RFC.
In Python there is a nice feature, that you can tell wich chars have to be safe urllib.quote(s, safe='~'). All chars except this one in the safe parameter are escaped.
With PHP you could do this only with a search & replace function which isn't very nice.
So i want to suggest, to add likewise one more parameter to the urlencode function.

Expected result:
----------------
echo urlencode("Test str \"'.-/", array('\'', '"'));

output:
Test+str+"'%2E%2D%2F

======

echo rawurlencode("Test str \"'.-/", array('\'', '"'));

output:
Test%20str%20"'%2E%2D%2F

Actual result:
--------------
echo urlencode("Test str \"'.-/");

output:
Test+str+%22%27.-%2F

======

echo rawurlencode("Test str \"'.-/");

output:
Test%20str%20%22%27.-%2F