(Bug 5221) Fix uninitialized value warning in DW::SiteScheme

Use of uninitialized value $rv in hash element
 at /dreamhack/home/8398-kareila/dw/cgi-bin/DW/SiteScheme.pm line 199.
(Bug 5221) Uninitialized value warnings in LJ::S2.

Use of uninitialized value $styleid in string eq at
 /dreamhack/home/8103-alierak/dw/cgi-bin/LJ/S2.pm line 61.

Use of uninitialized value $newlay{"i18nc"} in sprintf at
 /dreamhack/home/8103-alierak/dw/cgi-bin/LJ/S2.pm line 1246.

Use of uninitialized value $n in substitution (s///) at
 /dreamhack/home/8103-alierak/dw/cgi-bin/LJ/S2.pm line 2704.
(Bug 5221) More S2-related uninitialized value warnings.

Use of uninitialized value in string eq at
/dreamhack/home/8103-alierak/dw/cgi-bin/LJ/S2/IconsPage.pm line 69.

Use of uninitialized value $overriding_prop_name in hash element at
/dreamhack/home/8103-alierak/dw/cgi-bin/LJ/Widget/S2PropGroup.pm line 127.

Use of uninitialized value $prop_list_class in concatenation (.) or string at
/dreamhack/home/8103-alierak/dw/cgi-bin/LJ/Widget/S2PropGroup.pm line 189.