fix some memory leaks
Disable encoding combobox in layer properties dialog for OGR provider with OLCStringsAsUTF8==true (so when it doesn't work anyway). Patch from Minoru Akagi.
Merge pull request #548 from minorua/raster_memory_leaks

Fix some memory leaks Fix #6795
Merge remote-tracking branch 'origin/master' into requestsNonCamelcase
1st step adding proxy envs to mapserver