get rid of Boost library components

Boost is painful to install and deploy. Latest mess is #1074 and #1085 (closed).

As we use only two compiled Boost component libraries, the best solution is to rid of them for good. Dependence on Boost header-only components is less problematic. Copying the headers to our 3rdparty directory turned out to cause new difficulties, and will not be attempted again any soon.

• Cover all uses of iostreams by tests (#1086 (closed))
• Replace all uses of iostreams by direct calls to zlib and bzip2.
• Replace program_options
• Rm Boost installation from CMake scripts
• Rm CMP0167 (makes #1074 and #1085 (closed) obsolete)
• Restore CI for mac_arm (outcommented in !2840 (merged))