Use shorter keyboard accelerator notation

We can write "control" as "^" for conciseness, for the same effect.
Add shortcuts for Save and "Save As..." commands

These are the same typical shortcuts supported in most other programs.
Bump pom-scijava version to 1.70

Updated the pom-scijava dependency. 1.70 which includes these updates:
* scijava-common - supports loading multiple subclasses of Services
* imglib2 - bug fixes for CalibratedAxes
* scifio - Calibration bug fixes & fixes for several formats
Added IJService

Created an IJService interface, which all services in IJ2 now extend.

This allows scijava-common Context instantiation on IJService.class to
include all IJ2 services, without specifying an explicit list.
Renamed IJService -> ImageJService

For consistency with SciJavaPlugin : SciJavaService, SCIFIOPlugin :
SCIFIOService, etc...
Create a LUT browsing/selecting plugin