Version 2.0.0 beta 7 - Various improvements

This primarily a release with under-the-hood changes and some fixes from the b0rked beta 6 release.

New features:

• New since last visit indicator #63
• Impersonation partially reverted to old model, without giving full control: #57
• Allow configuration by .ini or .json file in OS-native configuration paths #78

Improvements:

• Ensure on Android the input is always visible #75
• Splash screen when installed as app #58

Fixes:

• Monthly digest: main figure wrapping #66
• Monthly digest: placeholders not being replaced #65
• Monthly digest: wrong culture and number formatting #66
• New sheets cannot be created #64

Other:

• Code conventions now enforced through .editorconfig #72
• Dropped Ubuntu 14.04 support (x64)
• Added Ubuntu 18.04 support (x64)