McXtrace: MAXIV_Bloch should have sensible defaults

[ebknudsen]

The default instrument parameters don't really yield anything on detectors. This should be set to something that actually gives a signal.

[ebknudsen]

This is related to #1099 as Bloch uses this component.

[ebknudsen]

Furthermore the instrument geometry was wrong - after the grating there were a few mistakes. A fixed version now exists. But pending fix to #1099 the instrument will not work as planned.

[ebknudsen]

Now in fact does transmit something. Still todo:

1. Cleanup
2. Default uses the 0th order grating transmission - this should be some other
3. Add the NIM grating option

for 2 and 3 separate issues have been setup

[farhi]

According to last comment, new issues are set, and this one is done.