mwArray convert to QImage and Mat

• This project based on Qt, Matlab 2015b x86 and opencv.
• The Mat-QImage conversion is moved to HERE.

Introduction:

Mat-mwArray来源于互联网，QImage-mwArray是自己写的，可能有疏忽的地方。

Mat-mwArray is obtained from the Internet, QImage-mwArray is created by myself, so it's unstable (

Change Log:

• 2018.01.09:

Set this part to submodule.

将该部分的转换独立为子模块。

• 2018.01.08:

Changed the variable names in mat_qimage_convert and added annotation. Tested all the function and fixed a small error.

修改mat_qimage_convert中的变量名称，加入详细的说明，并对所有的转换进行了测试。修复了小错误。

• 2017.12.16:

Updated mat_qimage_convert.cpp and now the Mat(QImage) can be converted to QImage(Mat) by deep copy(safer) or shallow copy(faster).

更新了 mat_qimage_convert.cpp，现在Mat和QImage可以用深拷贝（更安全）或浅拷贝（更快）的方式来进行转换。

• 2017.11.30:

Changed cv::at to cv::ptr in Mat-mwArray convert, but I didn't test it bucause I give up coding C++ with matlab.

将Mat-mwArray转换中cv::at访问改为cv::ptr访问，好像at比较慢，但是没有测试，因为我一个月前就放弃matlab混合编程了，太慢了

• 2017.11.13:

Added QImage-mwArray convert

添加QImage-mwArray转换