doc, leave a note about quantisation artefacts

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'doc/general'

* doc/general:
  doc, leave a note about quantisation artefacts
  doc, brag about --total-return|-T switch
  doc, brag about --reverse|-R option
Merge branch 'code/hygiene'

* code/hygiene:
  hygiene, provide prototypes for dfp754 inlines
  chore, obey gcc warnings
  hygiene, replace ctl_caev_t literal by ctl_zero_caev()
  chore, expand or condense initialisers so gcc will shut up
  chore, ask for -Wno-parentheses to turn spurious gcc warnings off
  chore, ask for -Wno-switch to turn spurious gcc switch warnings off
  minor, use c99 inlines (with possibly external linkage) in ctl-dfp754.h