Merge branch 'refs/heads/t/ff'

A short series which overhauls the ff server command.

Cooking for almost a year (for no good reason).

* refs/heads/t/ff:
  com_ff(): Fix bad grammar in help text.
  com_ff(): Depreciate "n-" syntax.
  com_ff(): Simplify code for jumping backwards.
  com_ff(): Avoid "unsigned i".

diff --cc NEWS.md
index 55ef3be947ee76d6b0937b33988b0cd960c0e985,55ef3be947ee76d6b0937b33988b0cd960c0e985..1aca9b0ae4825e295344c9dc29634785b79bcad3
--- 1/NEWS.md
--- 2/NEWS.md
+++ b/NEWS.md
@@@ -1,6 -1,6 +1,16 @@@
  NEWS
  ====
  
++----------------------------------------------
++0.6.3 (to be announced) "generalized activity"
++----------------------------------------------
++
++- The ff command now accepts a negative argument to instruct the
++  virtual streaming system to jump backwards in the current audio
++  stream. The old syntax (e.g., "ff 30-") is still supported but it
++  is deprecated and no longer documented. The compatibility code is
++  sheduled for removal after 0.7.0.
++
  --------------------------------------
  0.6.2 (2018-06-30) "elastic diversity"
  --------------------------------------

diff --cc command.c
Simple merge