New features from bata24/gef

[hugsy]

Check out https://github.com/bata24/gef and see what features can/should be imported here or in gef-extras

Related Issues/PRs:

• add onegadget plugin to gef #679 by @theguy147
• Backport Elf / ElfInfoCommand updates #717 by @Kileak

Use this Kanban for tracking
https://github.com/hugsy/gef/projects/6

[theguy147]

I added a PR (#679) for one of the features: the one_gadget plugin that I often use next to gef and I'm a big fan of including it like @bata24 did.

[jrozner]

It would be really nice to pull in find_fake_fast and visual heap

[hugsy]

Visual heap like this ->https://github.com/hugsy/gef-extras/blob/master/scripts/visualize_heap.py ?