Add applies_to field to Relocation

[yd0b0N]

This patch adds an applies_to field to the ELF.Relocation object that tracks with ELF.Section the relocation applies to in an ELF object file. It's value is provided by the ELF.Parser when the latter analyzes an ELF object file. When dealing with object files, the field is necessary to properly interpret the meaning of the relocation's address field because in this context, instead of representing a virtual address, the address is relative to the beginning of the designated ELF section.

[romainthomas]

Merged with 0bbeaa8.

I did small modifications, especially I replaced the name applies_to with section because the relocation could also apply to a segment, a symbol etc

Thanks for the contribution.