Convert core::Matrix from pyre::grid to Eigen (#858)

* Convert isce3::core::Matrix pyre -> Eigen

* Remove unused Cube class

* Remove unused Matrix.icc

* Remove commented code

* Check size_t/ptrdiff_t coercion

* Drop extraneous typename

* Throw error for invalid pixel/line offset

* Remove Row{Array/Matrix}XX aliases

* Fix shadowed template parameter

* Fix matrix base class

* Fix indentation

Author: rtburns-jpl

cxx/isce3/Headers.cmake

@@ -19,8 +19,6 @@ core/Baseline.h
 core/Basis.h
 core/Common.h
 core/Constants.h
-core/Cube.h
-core/Cube.icc
 core/DateTime.h
 core/DenseMatrix.h
 core/detail/BuildOrbit.h
@@ -42,7 +40,6 @@ core/LUT1d.h
 core/LUT1d.icc
 core/LUT2d.h
 core/Matrix.h
-core/Matrix.icc
 core/Metadata.h
 core/Orbit.h
 core/Peg.h