InputText: rename Edited->EditedThisFrame, add EditedBefore. (#701) + Comments + About box clipboard blurb include a comment.

imgui_internal.h

@@ -1245,7 +1245,8 @@ struct IMGUI_API ImGuiInputTextState
     bool                    CursorFollow;           // set when we want scrolling to follow the current cursor position (not always!)
     bool                    CursorCenterY;          // set when we want scrolling to be centered over the cursor position (while resizing a word-wrapping field)
     bool                    SelectedAllMouseLock;   // after a double-click to select all, we ignore further mouse drags to update selection
-    bool                    Edited;                 // edited this frame
+    bool                    EditedBefore;           // edited since activated
+    bool                    EditedThisFrame;        // edited this frame
     bool                    WantReloadUserBuf;      // force a reload of user buf so it may be modified externally. may be automatic in future version.
     ImS8                    LastMoveDirectionLR;    // ImGuiDir_Left or ImGuiDir_Right. track last movement direction so when cursor cross over a word-wrapping boundaries we can display it on either line depending on last move.s
     int                     ReloadSelectionStart;