fix the send button's enable state after sended text for iOS7
fix the send button's enable state after sended text for iOS7;
add XHMessageType.
Revert "fix the send button's enable state after sended text for iOS7;"

This reverts commit 36c78ee8bf05295fe268cc292c8b1e14c3e72bfc.
Revert "fix the send button's enable state after sended text for iOS7"

This reverts commit c6afc241ce46d797ec482aa175512c53536db197.
Merge branch 'master' of https://github.com/xhzengAIB/MessageDisplayKit into XH-master

# By Jack
# Via Jack
* 'master' of https://github.com/xhzengAIB/MessageDisplayKit:
  Update README.md
  Update README.md
  Update README.md
  Update README.md
  Update README.md
  fix the bug from iOS7
  Fix the copyZone method
  fix memory bug
  Update README.md
  delete png files.
  Add send voice message.

Conflicts:
	Example/MessageDisplayExample/MessageDisplayExample/XHDemoWeChatMessageTableViewController.m
	MessageDisplayKit/Classes/Controllers/XHMessageTableViewController.h
	MessageDisplayKit/Classes/Controllers/XHMessageTableViewController.m
Merge branch 'XH-master'

# By Jack
# Via Jack (2) and Aevit (1)
* XH-master:
  Update README.md
  Update README.md
  Update README.md
  Update README.md
  Update README.md
  fix the bug from iOS7
  Fix the copyZone method
  fix memory bug
  Update README.md
  delete png files.
  Add send voice message.

Conflicts:
	Example/MessageDisplayExample/MessageDisplayExample/XHDemoWeChatMessageTableViewController.m
	MessageDisplayKit/Classes/Controllers/XHMessageTableViewController.h
	MessageDisplayKit/Classes/Controllers/XHMessageTableViewController.m
Merge pull request #4 from xhzengAIB/master

Update codes
a bug when switch to record state if the inputed text is more than 2 lines
Merge pull request #28 from Aevit/master

a bug when switch to record state if the inputed text is more than 2 lines