Improvements in textedit and hotkey manager

* Set textedit's cursor position to the end of text in some situations
* Send hotkey messages to the current channel instead of default channel
* Allow to overwrite sprites using otml and pngs

src/framework/graphics/texturemanager.h

@@ -33,6 +33,7 @@ public:
     void poll();
 
     void clearTexturesCache();
+    void preload(const std::string& fileName) { getTexture(fileName); }
     TexturePtr getTexture(const std::string& fileName);
     const TexturePtr& getEmptyTexture() { return m_emptyTexture; }