Bugfix and differentiate between delete size and subap size

Subap size and delete size when searching can now be different.
Implement ROI, multiple input files

- Now allow for regio of interets on input files
- Allow multiple input files to be concatenated into one output file
Add clip function, coordinate switch

- Besides clip value, also allow a clip function to be passed along
- Allow either pixel center or pixel indices to be returned
Allow for pixel coordinate as index or center
Bugfix: need 0.5 pixel offset for CoG coordinates
Add squeeze option to read_file

.squeeze() gets rid of 1-element dimensions
Use read_file() squeeze option in convert
Added calc_zern_infmat()

calc_zern_infmat() calculates the influence of Zernike polynomials on a
SHWFS.
Added option to sort find_mla_grid() output
Add locate_acts() to find DM actuators

locate_acts() finds the DM actuators using influence matrices as input
data.
Also return intermediate data products
Improved documentation
Bugfix in calc_slope()

Fit matrix was incorrect, was fitting y = a*x, now fits y = a*x +
offset where offset is ignored.
Added interactive plotting to calc_zern_infmat()
Fix array ordering
Removed dead code