Fixed compilation errors with gcc10
Fixed issues with large COMBINE_BUFSIZEs.

Fixed errors with gcc -fno-common option (gcc10 default).
Added hint to MEM_MAX and VMEM_MAX in memory shortage error message.

Fixes some reprojection issues for large FOVs
New MJD-END keyword in output coadds
Adds Roy Henderson's patch for fpacked FITS input images (optional, on by default)
Bug fixes