FIX: progressbar: Print correct "mode:"

FIX: progressbar: Print correct "mode:"

The progressbar would always print "mode: write", even when the transfer
was resumed. This commit fixes this and melds "skip <transfer>" messages
into the lpbar (lpbar_print) output.

Notable changes:
* get/http.c: Do not print "skip <transfer>: <reason>" (see below)
* get/http.c: Relocate the lpbar_print call (+additional calls)
* pbar/lpbar.h: Add lpbar_mode={retrieved_already,forced_skip,...}
* pbar/lpbar.c: Reimplement lpbar_print
  - Remove 'gboolean skip_transfer' parameter
  - Print "skip <reason>" with "mode:"

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>