make Graph-Explorer's UI more suitable for newbies

* clear help & getting started section, pointing to wiki articles
* make suggested queries more useful for newbies
* remove tags from suggested queries, they were pretty pointless
* also urlquote suggested queries links, to make unit=B/s and such
* work
* remove 'Meta' page, move that informatio to wiki
* clarify monitoring_health dashboard and its flaws
new timeserieswidget, so we can modify axis config
support 'min' and 'max' to set Y-axis limits
remove tags in avg_by or sum_by, from group by

unless they were explicitly added in group by, in which case
we tell the user to not use the same tag in multiple things (like
before)
bugfix: ensure unique dash keys
clean up js update_graphs()
tighten design, clean html
properly show errors when query patterns can't be parsed
fix display of infos/errors

the class "row" caused the info msg to go further left than the query
input, which looked weird. looks like this class should only be used
for a real, screen-wide row. so removed it and nothing broke.
also cleaned up other related code

verified that infos and errors show fine. multiple errors go next to
each other, which seems fine
make the query parsing + response section pretty

also add Y-axis min/max stuff
make inspect view prettier