Support highlighting for PHP classes and functions/methods (#218)

Before classes and functions used the default foreground color which made it hard to distinguish them from variables and syntactic characters like braces. The new style now matches other ports and highlighting engines and makes it easy to identify these elements with Nord's authentic appearance.

Closes GH-218

colors/nord.vim

@@ -469,9 +469,12 @@ hi! link markdownHeadingDelimiter Keyword
 call s:hi("perlPackageDecl", s:nord7_gui, "", s:nord7_term, "", "", "")
 
 call s:hi("phpClasses", s:nord7_gui, "", s:nord7_term, "", "", "")
+call s:hi("phpClass", s:nord7_gui, "", s:nord7_term, "", "", "")
 call s:hi("phpDocTags", s:nord7_gui, "", s:nord7_term, "", "", "")
 hi! link phpDocCustomTags phpDocTags
 hi! link phpMemberSelector Keyword
+hi! link phpMethod Function
+hi! link phpFunction Function
 
 call s:hi("podCmdText", s:nord7_gui, "", s:nord7_term, "", "", "")
 call s:hi("podVerbatimLine", s:nord4_gui, "", "NONE", "", "", "")