r_bin: removed rva, offset and size from imports.

PLT-like lazy import wrappers are now part of symbols, where applicable.
The "imp." prefix is a temporary solution, it should be a flag.
r_bin: removed hint from RBinImport, as it's only used in PE and even there it's doubtfully relevant.
r_bin/ELF: don't ignore the r_addend field from Elf_Rela relocs.
r_bin: new generalized relocs, with only arch-independent types.

Basic implementation for ELF relocs (x86, x64 and ARM).
r_bin/PE: implement new relocs.
Mach-O: new relocs implementation and complementary fixes for imports.
r_bin/mach0: updated mach0_specs.h using original Apple headers where possible.
r_bin/mach0: new relocs using dyld_info bind opcodes.
r_bin: improved JSON output and VAPI for the new relocs.