stringOps: Rationalisation of expansions

Specific names have been given for expand functions. Unused functions
have been removed, and functions only used locally have been removed
from the namespace. Documentation has been corrected. Default and
alternative value handling has been removed from code template
expansion.

applications/test/dictionary/Test-dictionary.C

@@ -51,7 +51,7 @@ int main(int argc, char *argv[])
         dict.add("aaOpenFOAMcc", 1);
 
         string s("DDD${aa${WM_PROJECT}cc}EEE");
-        stringOps::inplaceExpand(s, dict, true, false);
+        stringOps::inplaceExpandEntry(s, dict, true, false);
         Info<< "variable expansion:" << s << endl;
     }