Grid extraction bug and enhancement

[Ed McDonagh]

Grid information extraction is wrong in rdsr.py, might not work in mam.py or dx.py for different modalities and model doesn't record focal distance

rdsr.py tries to put grid information in the wrong database table.

mam.py (and therefore dx.py as this element is the same) looks for specific text to create the grid table entries, such as FOCUSSED.

The grid focal length is not recorded.

[Ed McDonagh]

Updated models to add grid information. Refs #131

→ <<cset c57308cd6997>>

[Ed McDonagh]

Corrected grid focal length keyword, added it into the detail view to see if it works, which it does. Need to work on the grid type code. Refs #131

→ <<cset 5d03837e432d>>

[Ed McDonagh]

Grid type extraction and display now working with limited testing. Fixes #131

→ <<cset 4ea342a64570>>

[Ed McDonagh]

Removed display of grid type from detail html as not that useful. Refs #131.

→ <<cset 45667d5cc968>>