Add "right Click > Select Block" to the Hex Widget

[ITAYC0HEN]

It will be great to have the option to select a block of [size] for a given [address] or a range of [start_address] to [end_address] in the Hex Widget.

It would proobably should look something like this:

Ideally, it would have these features:

• select [start address] and [size]
• select the block from [start address] to [end address]
• whether the user chose to use either [end address] or [size], the other textbox would be updated appropriately. For example if my [start address] is 0x1a00 and I chose [size] to be 0x50, then[end address] would automatically be updated to be 0x1a00+0x50 which is 0x1a50.
• The text boxes would support math operations (i.e [start address] can be "0x40100 + 0x2a77")
• the feature would support different numeric bases such as Hexadecimal, Decimal and Octal.

Bonus:

• the dialog would treat both "0x5a4" and "5a4" as hexadecimal and will ignore the 0x
• support for math operations with memory. For example: start address would be [0x40a3]+0x500 so it would read a dword from the address 0x40a3 and will add 0x500 to it. iirc, this feature already being supported by the ? of radare2
• the selected block would be copied to clipboard (upon using a checkbox/dedicated button)
• backward slection support. For example f [start address] is "0x500" and [size] is "-0x200", the selected block would be from 0x300 to 0x500

[jamieb122]

See pull request #770