update about the perf.libreoffice.org site

Hey,

so there has recently been some activity around the perf.libreoffice.org
(if you are not yet familiar with the site check it out) website and we
have now some exciting new features. As always most of the work has been
done by Norbert (so if you use the site and meet him at a conference
remember that the poor soul has to live with American beer all year ;) ).

So the new features are:

* In the details view you have buttons for 30 and 360 days as well as for
all the data.

* The details view also has a slider above the chart to zoom into some
parts of the data. This complements the above mentioned feature.

* The database table has now a column for comments. This allows us to store
a comment for each test commit combination. Please use that if you have
introduced a performance regression or improved the performance and leave a
comment stating which commit is responsible. For now the corresponding
entry can only be changed on the server so please ping Norbert or me with a
link to the test, the commit id and the text.

* if you disable a data series it no longer shows the old value

There are a few more changed that are not visible to the user. If you are
interested in them or making the whole site more beautiful please have a
look at https://gerrit.libreoffice.org/gitweb?p=perfdbmgr.git;a=summary

There are still a few planned improvements:

* Only show one or two series by default

* Have a double click listener opening the commit in cgit.freedesktop.org
when clicking into the chart

* description as hover text when it exists

* Button from the details view back to the suite page.

If you have more ideas please let us know. Or even better implement them on
your own.

Regards,
Markus