Backport 470 0.8.x

[BenjamenMeyer]

Thank you for submitting a pull request and becoming a contributor to the Vega Strike Core Engine.

Please answer the following:

Code Changes:

• Have the PR Validation Tests been run? See https://github.com/vegastrike/Vega-Strike-Engine-Source/wiki/Pull-Request-Validation
• This is a documentation change only

Issues:

• Py3 engine segfaults when using a savefile from a py2 engine #149, Don't utf8-check New_Game #470

Purpose:
Backport #470 to 0.8.x - a slight tweak of #463 to prevent overlaps with the in-game constant saved game name of New Game
Thanks @P-D-E for the work!

Test Details:

• Test 1: Start game; select Load, select an invalid UTF-8 saved game; click load.
• Test 2: Start game; start a new campaign; go to the concourse; click save/load; select an invalid UTF-8 saved game; click load

In both cases it should fail to load the game and present a message to the user.

[P-D-E]

👍