Port to IDA 7.4 with Python 3 / no deprecated API

[saidelike]

Atm it doesn't work with Python 3:

C:\Users\user\AppData\Roaming\Hex-Rays\IDA Pro\plugins\lighthouse_plugin.py: Missing parentheses in call to 'print'. Did you mean print(prefix_message)? (log.py, line 21)
Traceback (most recent call last):
  File "C:\Program Files\IDA Pro 7.4\python\3\ida_idaapi.py", line 590, in IDAPython_ExecScript
    exec(code, g)
  File "C:/Users/user/AppData/Roaming/Hex-Rays/IDA Pro/plugins/lighthouse_plugin.py", line 1, in <module>
    from lighthouse.util.log import logging_started, start_logging
  File "C:/Users/user/AppData/Roaming/Hex-Rays/IDA Pro/plugins\lighthouse\util\__init__.py", line 3, in <module>
    from .log import lmsg, logging_started, start_logging
  File "C:/Users/user/AppData/Roaming/Hex-Rays/IDA Pro/plugins\lighthouse\util\log.py", line 21
    print prefix_message
                       ^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print(prefix_message)?

I haven't checked for the deprecated APIs but that would need to be checked too.

[gaasedelen]

All done! #79 -- Py3 changes (and more) are on the DEVELOP branch if you want to start using them now, rather than waiting for the next release.