Add length in the blob, char , varchar column and generate data according to option provided by user.

Also add support for tiny blob, medium blob, 

Column prefix, and default length:-> 

bt => Tiny BLOB, Maximum_length/4
bm => Medium Blob, Maximum_length/3
b => blob,  Maximum_length/2
bl => LONG BLOB, Maximum_length

tt => Tiny Text,  Maximum_length/4
tm => Medium Text,  Maximum_length/3
t => Text,  Maximum_length/2
tl => Long Text,  Maximum_length