R30 stats

Remove uses of events.content

Use iteritems over item to loop over dict
formatting

phone home cache size configurations

Revert "improve mxid check performance"

Replace old style error catching with 'as' keyword

Add basic performance statistics to phone home

improve mxid check performance

Use static JSONEncoders

json encoders have an encode method, not a dumps method.

Use simplejson throughout

Signed-off-by: Adrian Tschira <nota@notafile.com>

using json.dumps with custom options requires us to create a new JSONEncoder on
each call. It's more efficient to create one upfront and reuse it.

Let's use simplejson rather than json, for consistency.

Measure time it takes to calculate state group ID

Fix error when claiming e2e keys from offline servers

fix tests/storage/test_user_directory.py

count_daily_users failed if db was sqlite due to type failure - presumably this prevcented all sqlite homeservers reporting home

Linearize calls to _generate_user_id

Remove last usage of ujson

Add counter metrics for calculating state delta

This requires the psutil module, and is still opt-in based on the report_stats
config option.