Made user_limits.test scheduling independant (this solves failure on QNX).
Made sys_var_max_user_conn variable int sized. Changed
max_user_connections from ulong to uint to be able to use it in
sys_var_max_user_conn::value_ptr() (solves failures on 64-bit platforms).
of concurrent connections for the same account)"
Added support of account specific max_user_connections limit. Made all
user limits to be counted per account instead of the old behavior,
which was per user/host accounting. Added option which enables the old
behavior. Added testing of these to the test suite.
(After review version).
