Simulate enzyme methylation through lowercasing

[Koeng101]

https://github.com/TimothyStiles/poly/blob/2d5d8c4551121fca4c394835efd89bffb0c3c5ca/clone/clone.go#L124

An idea came to me because of this line in our clone package:

"BsaI":  {"BsaI", regexp.MustCompile("GGTCTC"), regexp.MustCompile("GAGACC"), 1, 4, "GGTCTC"},

The regex only targets capitalized letters, which we enforce in the clone function. However, I need a way to simulate methylation of sequence - what if we used lowercase sequences in place of methylation? Instead of forcing capitalization, we could have flag for methylation.

This would be pretty easy to implement and would help me a bunch. Gonna reference in a new PR