ReadAlignment.isFrontExtension

Returns true iff the read alignment is an front extension, ie. it is an extension and reaches over the front of the reference contig.

1 Case 1 (complement alignment):
2 
3                   0  rx
4     ref           |--+->-+->-->-->--|
5                      | | |
6     read  |--<--<--<-+-<-+--|
7           0          ax
8 
9 Case 2 (non-complement alignment):
10 
11                   0  rx
12     ref           |--+->-+->-->-->--|
13                      | | |
14     read  |-->-->-->-+->-+--|
15           0          ax