gitweb: Make 'history' view (re)use git_log_generic()

Make git_history use git_log_generic, passing git_history_body as one
of its paramaters.  This required changes to git_log_generic, in
particular passing more things as parameters.

While refactoring common code of 'log', 'shortlog' and 'history' view,
we did unify pagination, using always the form used by 'history' view,
namely
  first * prev * next
in place of
  HEAD * prev * next
used by 'log' and 'shortlog' views.

The 'history' view now supports commit limiting via 'hpb' parameter,
similarly to 'shortlog' (and 'log') view.  Performance of 'history'
view got improved a bit, as it doesn't run git_get_hash_by_path for
"current" version in a loop.  Error detection and reporting for
'history' view changed a bit.

Signed-off-by: Jakub Narebski <redacted>
Signed-off-by: Junio C Hamano <redacted>