Snippets: Allow lowercase/titlecase/uppercase modifiers for variables

Use the same syntax already used in the custom wizard to denote
variables that are modified to be lower-/title-/uppercase:

 $tESt:u$ will become TEST
 $tESt:c$ will become TESt
 $tESt:l$ will become test

The snippet will be inserted without any name mangling happening.
Once the editing is done the name mangling is applied to all fields.

Change-Id: I7c1f5a1ad2bb5acf1b88b54de51bb39391c64763
Reviewed-by: David Schulz <david.schulz@digia.com>

src/plugins/texteditor/snippets/snippet.h

@@ -36,8 +36,19 @@
 #include <QList>
 #include <QString>
 
+namespace Core { class Id; }
+
 namespace TextEditor {
 
+class TEXTEDITOR_EXPORT NameMangler
+{
+public:
+    virtual ~NameMangler() { }
+
+    virtual Core::Id id() const = 0;
+    virtual QString mangle(const QString &unmangled) const = 0;
+};
+
 class TEXTEDITOR_EXPORT Snippet
 {
 public:
@@ -73,9 +84,10 @@ public:
         QString text;
         bool success;
         struct Range {
-            Range(int s, int l) : start(s), length(l) { }
+            Range(int s, int l, NameMangler *m) : start(s), length(l), mangler(m) { }
             int start;
             int length;
+            NameMangler *mangler;
         };
         QList<Range> ranges;
     };