Only migrate settings if first start=false

[CoBC]

When migrateSettings() is call with a blank ini file, a lot of settings aren't incorrectly set to empty values, E.G. sound events. Also some keys aren't incorrectly redefine, E.G. gender define to female instead of neutral.

[CoBC]

@bear101 it seams some config keys are also migrate incorrectly in existing config, E.G. all sound events are disabled when running 5.17 on an existing 5.16.1 config.
I don't really understand why, do you have an ideA? I think we should fix this and than release a 5.17.1 because it's a major bug for a lot of users.

[bear101]

With this change the following code is not called in migrate settings:

    if (ttSettings->value(SETTINGS_GENERAL_VERSION).toString() != SETTINGS_VERSION)
        ttSettings->setValue(SETTINGS_GENERAL_VERSION, SETTINGS_VERSION);

Also SETTINGS_GENERAL_FIRSTSTART was first introduced in v5.8 so settings prior to that will not be migrated.

[CoBC]

Ah, yes, you're right. also I guess all other fixes are sufficient, so closing this PR