Manually selecting fd is still valid and it should override maps fdselection. This is.. We need a way to tell r2 to view one fd or all of them. In case of having two files mapped on the same address space we will select the last opened.
The base address is used to reallocate all vaddr offsets.
Reading/writing ops should be done in a loop checking for the section boundaries.
The sections must be associated to a file, but we should be able to display/use them all in case of having non forced fd. This is, when not having overlapped files in memory.