Better support for compressed sections

[eliben]

The .so file from #336 fails full readelf comparison because pyelftools doesn't handle compressed sections sufficiently well. Even in a basic header output, readelf marks compressed sections with a "c" like in:

[28] .debug_aranges mips_dwarf 00000000 00a448 002a1d 00 c 0 0 4<<

But pyelftools cannot do that yet.