ObsCore implementation
Implement ObsCore and David Andresic's changes
added Source Types
SpecCutter - apply on multiple spectra

Added multiple spectra selection (instead of the current selected one)
in  Plot window's 'Analysis' - 'Cut regions from spectrum' menu.
Stack to FITS and all SAMP spectra to the same window

Added functionalities:

- Saving the current list of spectra to the FITS file (one IMAGE
extension per spectrum)

- Checkbox under 'Interoperability' for showing the spectra from SAMP to
the same window
Reading stack in FITS, Opening multi-HDU FITS

- added reading stack saved as FITS capability
- added capability of opening multi-HDU FITS files
Merged changes from David Andresic

Reading stack in FITS, Opening multi-HDU FITS
- added reading stack saved as FITS capability
- added capability of opening multi-HDU FITS files
Stack and multi-HDU FITS, Echelle Support

merge changes from David Andresic
Merge changes from David Andresic

Reading stack in FITS, Opening multi-HDU FITS
- added reading stack saved as FITS capability
- added capability of opening multi-HDU FITS files
Merged changes from David Andresic

Reading stack in FITS, Opening multi-HDU FITS
- added reading stack saved as FITS capability
- added capability of opening multi-HDU FITS files
test if ucd is null before comparing
Merged changes from David Andresic

Reading multi-HDU FITS fix
change in parameter name
Merged changes from David Andresic
Merged changes from David Andresic:

Stack to FITS (image) and all SAMP spectra to same windows
Merged changes from David Andresic

Visual selection of spectra and their highlighting after selection
added clear button and tooltip text
Use ContentType from HTTP header determine the format of the spectra
new minor version