#130 Proposal: -x option, flash then execute

[Renaud Fivet]

Once start address can be obtained directly from ihex file, it will be handy to be able to simply write
stm32flash -x file.hex COMx
to be equivalent to
stm32flash -w file.hex -g some_address_here COMx

Attached is a patch that works with the ihex address parsing patch I submitted for ticket 121.

[Renaud Fivet]

Patch updated based on v0.7