Merge pull request #1230 from flaviut/fix1226

Fix 1226 and document associated methods

compiler/ccgtypes.nim

@@ -13,8 +13,8 @@
 
 proc mangleField(name: string): string =
   result = mangle(name)
-  if name[0] in 'a'..'z':
-    result[0] = name[0].toUpper
+  result[0] = result[0].toUpper # Mangling makes everything lowercase,
+                                # but some identifiers are C keywords
 
 proc isKeyword(w: PIdent): bool =
   # nimrod and C++ share some keywords

compiler/ccgutils.nim

@@ -162,6 +162,9 @@ proc makeSingleLineCString*(s: string): string =
   result.add('\"')
 
 proc mangle*(name: string): string =
+  ## Lowercases the given name and manges any non-alphanumeric characters
+  ## so they are represented as `HEX____`. If the name starts with a number,
+  ## `N` is prepended
   result = ""
   case name[0]
   of Letters: