pixelpipe_hb: run style beautifier
fix some off-by-one errors in histogram calculation
(cherry picked from commit 25ba2cc281912e0197cdb4fdde9f03a0089f7605)

Conflicts:
	src/develop/pixelpipe_hb.c
Increase readability of text on histogram
(cherry picked from commit 0b68d00de816abe8077102fb4962b3b73cd9854f)
navigation: run style beautifier
navigation: increase readability of text on the preview thumbnail