Initial version of bfCheckJavaMemory

This displays a warning message if the heap space is below 512m.  Only
functions that call setId currently call bfCheckJavaMemory.
Update copyright year
Allow the minimum memory value to be specified

The default value is still 512m.
bfCheckJavaMemory: fix typo in function definition
bfCheckJavaMemory: use 'warning' instead of 'fprintf' for logging
Change warning ID from 'bf' to 'BF:lowJavaMemory'

...as suggested by @sbesson.
Add unit test class for bfCheckJavaMemmory() function
Combine warning messages to have one warning with specified ID
Implement pre-loading for .sdt files in the interest of performance as an option.
Extend pre-load option to allow smaller sub-planes & address format issues.
Further format issues.
Split initialisation of channel & time bin into preLoaded & not.
merge develop -D org -I include -E exclude: PR 528 (Tile performance improvements for VMS and NDPI)
merge develop -D org -I include -E exclude: PR 857 (Initial support for Zeiss .lms files)
merge develop -D org -I include -E exclude: PR 858 (Initial support for Veeco AFM data)
merge develop -D org -I include -E exclude: PR 859 (Assorted metadata/tile parsing fixes)
merge develop -D org -I include -E exclude: PR 866 (Update POMs to point to mirror of the cppwrap plugin (rebased onto develop))
merge develop -D org -I include -E exclude: PR 884 (Make a buildable source release)
merge develop -D org -I include -E exclude: PR 885 (Correctly set Modulo annotations for multi-Image datasets)
merge develop -D org -I include -E exclude: PR 886 (Flex: be more permissive in parsing IFDs and XML)