indentation in externalInput component.cpp, plus addition of a
skeleton "externalInput2" which is almost sure to be removed again!
Code tidying
Handle case that sendVal is not set to a suitable value
Error out if dataType is not set correctly.
Hardcode dataType for now
Don't need to create a new externalInput2 for matlab connections, as the mex function scheme will work with existing externalInput
Code tidying
Adds connection name to externalInput/Output connection handshake.

The connection name comes from the experiment.xml, translated by
SpineML_External[In/Out]put_NL.xsl

This changeset also includes a clarifying change of a function
argument for the data size.
Adds option to skip SystemML creation
Merge branch 'matlab_comms'

Conflicts:
	tools/externalInput/brahms/0/component.cpp
	tools/externalOutput/brahms/0/component.cpp

These conflicts occurred because I made the mistake of doing lots of
re-indentation in a non-master branch.