negative and decimal switch label values (#569)

allows for every possible option including:
`set cino+=:-0.5s`
`set cino+=:-.5s`

Author: bounceme

indent/javascript.vim

@@ -195,7 +195,7 @@ function GetJavascriptIndent()
   if index(map(synstack(v:lnum, 1), 'synIDattr( v:val, "name")'),'jsSwitchBlock') > -1
     let bnum = search('\<switch\s*(','nbw')
     let switch_offset = bnum < num || bnum == lnum ? 0 : &cino !~ ':' ?  s:sw() :
-          \ matchstr(&cino,'.*:\zs[0-9.]*') * (match(&cino,'.*:\zs[^,]*s') ? s:sw() : 1)
+          \ float2nr(str2float(matchstr(&cino,'.*:\zs[-0-9.]*')) * (match(&cino,'.*:\zs[^,]*s') ? s:sw() : 1))
   endif
   if (line =~ g:javascript_opfirst ||
         \ (getline(lnum) =~ g:javascript_continuation && getline(lnum) !~ s:expr_case) ||