SolidCraft 0.30.1a for Android

SolidCraft 0.30.1a for Android (SolidCraft 0.30.1, port release a).

Built from upstream SolidCraft v0.30.1 (8e2b0cd6) with the Android port on top.

New in 0.30.1a:

• Upstream 0.29.0, 0.30.0 and 0.30.1 (442 commits): Preferences in twelve pages, saved as they change; lasso selection; Measure from your selection; Plane through an axis and a point; keep and compare renders; inch fasteners; security fixes. Designs are format 49.
• An OpenGL ES fallback (#4): when a phone's graphics can't start, the app leaves cleanly instead of being aborted, the next launch uses OpenGL ES, and startup-error.txt in the app's folder says why.
• The 3D view draws on OpenGL ES: upstream 0.30.1's viewport shader doesn't compile there; the port fixes it.
• Crash reports you can save: shown at the next start, Save a copy through Android's picker; Report a bug drafts the issue on this port's tracker.
• Tested on Vulkan and OpenGL ES: docs/android-0301a-test.md.

Install: download SolidCraft-0.30.1a-android-arm64.apk on an Android 8.0+ phone or tablet (arm64) and open it, allowing installs from that source; or adb install -r SolidCraft-0.30.1a-android-arm64.apk. Signed with a development key: uninstall a build from elsewhere first if Android refuses to update it.

Works: the full SolidCraft app (sketches, features, the timeline, the Render workspace) on Vulkan or GLES; mouse and keyboard as on the desktop (hover, selection, navigation buttons, wheel, right-click menu, shortcuts); touch (one finger orbits, tap selects, two fingers pan, pinch zooms, a finger drags a dialog's arrows); Back closes what is open; open, save, import and export through Android's file picker (STEP, STL, 3MF and OBJ tested); the on-screen keyboard for typing. Port-only: helical B-rep, custom and clearance threads (docs/android-threads.md) and involute gears: spur, helical, herringbone, internal, rack, bevel, miter, worm, worm wheel, crossed helical (docs/android-gears.md). The port saves designs one file format past upstream's release, so upstream's releases ask to be updated instead of opening them; export STEP to share.

Not yet: the on-screen keyboard covers the lower half of the screen (the app doesn't move above it), the phone layout is usable but cramped (best on a tablet or a foldable's inner screen), autosave recovery. Known issues, with work-arounds: docs/android-known-issues.md. How to use it: docs/android-touch.md; details: docs/android.md.