less: fully implement -R

[FriendlyNeighborhoodShane]

The switch was half-implemented earlier and it only used to trim escape
sequences. This patch series implements the feature fully i.e. makes
it emit color (SGR) sequences raw, and fixes other behaviour around it.

Changes from v1:
 - count_colctrl does better validation for SGR sequences

Changes from v2:
 - fixed corrupted patches (accidentally edited before sending)
 - fix code style