ENH: Extract TiffReaderInternal to separate file

Refactored private class to be in separate private header.

Change-Id: Icb4008c1605a3a0b62c563350cf2e3bbe948ec6d
ENH: Refactor ReadTwoSamplePerPixelImage into template function

Reduce code duplication by using template method.

Change-Id: I45f417486e60a4d3e67ff31fa967dac069b3ce3e
ENH: Refactor GenericReadImage into template function

Reduce code duplication by using template method.

Change-Id: I79411ad6595258d54cbfa5a4152cc55994acd8e0
Merge topic 'TIFFRefactor'

690cfdc8 ENH: Refactor GenericReadImage into template function
5f73f24b ENH: Refactor ReadTwoSamplePerPixelImage into template function
0b573136 ENH: Extract TiffReaderInternal to separate file