ui-shared: remove toggle_ssdiff arg to cgit_diff_link()

This argument is never used with a value other than zero, so remove it
and simplify the code.

Signed-off-by: John Keeping <john@keeping.me.uk>
Change "ss" diff flag to an enum

This will allow us to introduce a new "stat only" diff mode without
needing an explosion of mutually incompatible flags.

The old "ss" query parameter is still accepted in order to avoid
breaking saved links, but we no longer generate any URIs using it;
instead the new "dt" (diff type) parameter is used.

Signed-off-by: John Keeping <john@keeping.me.uk>
ui-diff: add "stat only" diff type

This prints the diffstat but stops before printing (or generating) any
of the body of the diff.

No cgitrc option is added here so that we can wait to see how useful
this is before letting people set it as the default.

Suggested-by: Konstantin Ryabitsev <mricon@kernel.org>
Signed-off-by: John Keeping <john@keeping.me.uk>
ui-shared: show absolute time in tooltip for relative dates

Signed-off-by: John Keeping <john@keeping.me.uk>
Merge branch 'diff-summary' into pu

* branch diff-summary:
  ui-diff: add "stat only" diff type
  Change "ss" diff flag to an enum
  ui-shared: remove toggle_ssdiff arg to cgit_diff_link()
  ui-shared: remove toggle_ssdiff arg to cgit_commit_link()

Suggested-by: Konstantin Ryabitsev <mricon@kernel.org>
Merge branch 'time-tooltip' into pu

* branch time-tooltip:
  ui-shared: show absolute time in tooltip for relative dates

Add the absolute time as the title for spans containing a relative date.
Merge branch 'jk/compat-timegm' into pu

* branch jk/compat-timegm:
  compat/timegm: new compat function for systems lacking timegm()

Submitted to cgit@hjemli.net but not applied.

Need to see if there is an alternative to introducing a compat function.
Doing the back and forth in the local timezone is mostly good enough,
but doesn't handle DST correctly.
Merge branch 'log-follow-files' into pu

* branch log-follow-files:
  log: allow users to follow a file
  shared: make cgit_diff_tree_cb public

In its own branch upstream.

# Conflicts:
#	ui-log.c
Merge branch 'test-improvements' into pu

* branch test-improvements:
  WIP

WIP improvements to make the test suite more robust.
Merge branch 'scan-exclude' into pu

* branch scan-exclude:
  Add scan-exclude option to filter out repositories

An experiment to handle a certain use case.  Probably not desirable.