ds9 region import & WCSLIB integration

• a new functionality: an initial support for importing ds9 region files (*.reg) with image/physical/wcs (fk5 only) coordinates and two types of shapes: circle and point (hint: a menu setting FITS / import ds9 region)
• incorporated the WCSLIB library server-side (in the CSV export FORTRAN code ) as well as in the client-side JavaScript (calling the WASM-compiled C code), which replaces a custom implementation of the WCS conversion routines and provides a better compatibility with ds9
• a minor fix to the CSV export functionality (fixed the RA string parsing in the server C code)