Implement SASL plain authentication

Remove a useless std::move() and copy

Remove a useless “givin up” debug line

Use the right int64 type for INTEGER rows in the db

Use return {...} instead of make_tuple

Add a missing "virtual", and remove a trivial "private" redundancy

Disable the throttle limit if negative

Also, invalid values result in -1 being set

Fix one more warning

MaxHistoryLength now has some sensible default value if the user set a negative one

Add two missing ref

Fix the real_type of ThrottleLimit

Remove a bunch of useless empty lines

Fix a compile error with GCC 5.x

fix #3366

Trivial syntax improvements

Throttle all commands sent to IRC servers

fix #3354

mam: Send “fin complete” only when appropriate

Also simplify how we did the whole “limit + 1”
And fix one bad interpretation of the XEP for the case where the query has
no after or before restriction.

fix #3349

Missing fields in a data-form response are now interpreted as an empty value

Only use the ID to order archives

fix #3343

Revert "Use a different Date data type"

This reverts commit 857c7d3972a03cbeebf730d99b924d3710dee6a0.

Revert "Use the Date to find a next page in RSM, not the id"

This reverts commit 5ef7ba08028065b03d51d1dc70bb35aeb41ae19d.