Support Grid Matrix layout video merge

Support Grid Matrix layout video merge,
#8 Fix Orientation issue for Grid & parallel merge,
#9 Add multi Audio support for Grid & parallel merge,
Parallel merge function deprecated use Grid merge matrix layout to achieve this.

Add audio support for parallel & Grid video merge

1.5.9

1.5.9 #7 Add audio support

Add side by side parallel videos Merge

1.5.8

1.5.8 #6

1.5.7

1.5.7 #5

Swift Package Manager

1.5.6

Add Swift Package Manager

1.5.5

pod issue solved & Add Carthage

1.5.4

Add grid merge videos method, can merge 4 videos with grid layout

1.5.3

Add grid merge videos method, can merge 4 videos with grid layout

Swift 5

1.5.2

Pod 1.5.2

Swift 5

1.5.1

Update README.md