Codying style in accurate PV

This is the first of a patch series to
rearrange and simplify accurate PV.

In this patch there is simple coding
style and reformatting stuff.

Verified with fishtest it does not crash
with MAX_PLY = 8

No functional change.
Fix fen output for castling rights

This is a regression from 428962a

We have to cast to char here, otherwise the compiler
interprets it as an integer, and writes a number.

No functional change

Resolves #122
Fix some comments

No functional change.

Resolves #123