Infer Frame from breakend format for SVs

[ckandoth]

VCF specs define the breakend format as follows:

REF ALT   Meaning
s   t[p[  piece extending to the right of p is joined after t
s   t]p]  reverse comp piece extending left of p is joined after t
s   ]p]t  piece extending to the left of p is joined before t
s   [p[t  reverse comp piece extending right of p is joined before t

This should map to Frame info as follows:

t[p[    5to3
t]p]    3to3
]p]t    3to5
[p[t    5to5