Add compatibility for Python 3 [ida 7.x syntax]

[galaxyhaxz]

Beginning in IDA 7.4 python 3 was introduced and some of the syntax changed. Currently 'sym' will generate scripts containing calls like 'MakeName' that now have different names. I'd say for maximum compatibility we should have a command line arg to set old version Ida, but by default assume python 3.

Cheers, Andi.

[galaxyhaxz]

For reference (too tired to fix atm):
https://www.hex-rays.com/products/ida/support/ida74_idapython_no_bc695_porting_guide.shtml

IDA 7.4+ actually do support the older API but it's deprecated and disabled by default.
MakeComm should be renamed to set_cmt

[mewmew]

Sounds good. I think we can safely ignore compatibility for older versions of Python, as Python 2.x is officially dead as of 2020-01-01. Lets just update to the newest version of the API.