refs #10088 Failing attempt to change loading

(does not work correctly)
refs #10088 Change necessary for working without precompiled headers
refs #10088 Map is build seems correctly but detID-s are still wrong
refs #10088 Mainly done, checks and optimization is needed
refs #10088 Got rid of m_spectra_list in favor of m_specNum2SpecID map
refs #10088 Unit tests to check the changes and correct behavior

+ final bugs fixed for LoadISISNexus2
refs #10088 Doxygen errors
refs #10088 GCC warnings
refs #10088 Prospective Coverity warnings
refs #10088 a bit more tests for different options

especially correspondence between spectra and detectors maps.
Merge remote-tracking branch 'origin/bugfix/10088_PartialSpectraLoading'