Add option to generate camelCase names

[ksilin]

Currently, if the JSON contains snake_case names, these are used as-is in the case classes:

an option to convert abz_xyz in the JSON to abcXyz in the case class would be nice.

[waxzce]

sure, do you still need it ?

[ksilin]

not urgently :) ended up manually renaming and tweaking the Json with circe accordingly for the use case in question. But I work with APIs often, there will be ample opportunity to test the feature, since snake case is quite common.