Workaround for the svr_writer thread (of DOOCS) to block location mutexes for a very long time if many big D_spectrum are written. The write is now only done if necessary (i.e. after a modification) and the lock is released for a short period of time to make sure RPC calls don't get blocked for too long.

Improve location locking in updater

 - Preallocate the unordered set with worst-case size before the loop
 - Perform insert and lock in one step using the return value of insert

Allow to set the data matching mode. This for now only allows to switch off the DataConsistencyGroup matching for the attached macro pulse number.

Do not throw exception if the eq_fct_code in the DOOCS config file is not 10 and no code has expilicitly specified in the DoocsVariableMap.xml file.

throw error if a read-only spectrum is defined with more than one buffer

Fixes #28

Started implementing consistent macro pulse numbers in process variables. Only scalars at the moment.
No dediacted tests yet, but adapted ZMQ test which failed.

It breaks on bionc (don't know why)

This reverts commit cdd0598b.