* dgud/mnesia/slow-startup/OTP-14829:
  mnesia: Read schema user properties directly

Doing a proper transaction handling of user properties (in current
implmenentation) caused schema_transactions to be quadratic which
caused huge startup times for nodes with many tables since the merge schema
is a schema_transaction.

Do a direct read instead, cheap but implies that the plugin changes
will not be visible until the changes are commited and cannot be used
later in same transaction, which was possible before if undocumented
functions where used.

The "root cause" error reason was lost when abort_write failed,
e.g. file was already closed, and Mod:abort_write(..) returned an
error.

Set fixtable false will fail on deleted tables, catch that and also
report checkpoint deactivate error, so user can see why checkpoint
was deactivated and backup fails.

* richcarl/mnesia/table_info_order:
  Preserve key order in mnesia:table_info

Helps when mnesia_tm gets drowned in dirty_writes from remote node.

* dgud/mnesia/fix-blocked/OTP-13970:
  Avoid some error reports when stopping mnesia
  mnesia: Fix double blocked tables which could cause a crash

Worker processes can cause error reports if the main mnesia processes
dissapear.

Fast restarts could cause table to be blocked twice.