Replace a use of strcpy with memcpy, fixing a crash due to inlining.

On Linux, a use of strcpy caused a crash for unknown reasons when
inlined by -O2, but memcpy does not crash in the same place.
swig bindings: Remove extra scope around temporary sigval.

In SWIG 2.x, (and maybe 1.3?) this extra level of scope causes the
sigval to be destroyed even though a pointer to it is retained and
used shortly after, causing a crash.
swig: Change naming of extended struct to comply with how SWIG 2.x handles structs.
Use strcmp() instead of strstr() when trying to match signal names in monitor - this was preventing monitors from registerings new signals if their name was a substring of an existing signal.
Added benchmark for expression engine.
Fixed bug in signal history reallocation; initialize to zero.
Added db functions for retrieving exact signals from database; restored substring-matching to cmp_match_signal_device_name().
Modified db update functions to return the number of parameters added or modified. Use this information to only call handlers with MDB_MODIFY if params have actually changed.
Restore testmonitor screen clearing.
Added missing db functions to python bindings.
Free memory used by mapper_connection
Added new db functions to DLL export list, realphabetized.
Reworking handling of active instances to enable unsynchronized instance lifetimes.
Removed functions for declaring new instances and for setting instance stealing logic, added functions for user-code to discover oldest or newest active instance. Fixed various bugs in new signal-side id_map scheme, though tracking map status is still buggy.
Update testinstance for new instance management approach.
Fixed typos and signal handler arguments in tutorial.
Fixed bugs setting id_map release flags, memory freeing when freeing device, pointer bug.
Renamed instance id record to index to better reflect its usage; fixed potential overflow bug in msig_reserve_instances().
Fixed flag arguments calling msig_get_instance_with_local_id(), leaning up TODOs.
Revert to freeing signals first in mdev_free, but make sure not to reference freed signal when freeing connections.