A couple of patches, and other observations on pgadmin3

Hi pgadmin3,

There are a couple of places where variables look like they should be
const. On my system, pgadmin3 will not build without these changes,
bombing out with:

error: invalid conversion from 'const wxChar*' to 'wxChar*'

I should note that I'm using other hackery to allow a build with a
non-Unicode wxGTK (2.8). It appears (from Google) that this kind of
build failure only happens with non-Unicode wxGTK - though I can't
imagine why that would be!

I have to ask, why are you installing files world writable? (
http://svn.pgadmin.org/cgi-bin/viewcvs.cgi?rev=7141&view=rev )

Surely it's better to not install the cache file at all? Presumably
it's an optional file, given the filename!

Cheers,

Dave