Plus42 Equations, Preview Release

[Thomas Okken]

New update:

1. XEQ() didn't work in equations called from SOLVE or INTEG. Fixed.
2. When switching to a skin that only allowed 2 rows, while a 2-line message was in the display, the display would not get refreshed. Fixed.
3. Fixed NULL when pressing and holding unit keys.
4. Short, left-handed landscape, and right-handed landscape skins, now built into the Android and iOS versions. (This is causing the apps to grow by 1.5 megabytes; that bloat will go away when I integrate the logic to generate these skins from the original Plus42 skin into the apps themselves.)