Scripts: bumpver shouldn't commit

Now that tags control the build suffix, don't need to commit.

Bump version to 1.6-alpha2

Bump version to 1.6-alpha1

MGTK: Fix regression in detecting no-op thumb drags

Regressed in 071b9dc as a zero page location that was previously
believed safe to store the old thumb location is now trashed. Use SMC
instead; costs a couple of bytes but much less fragile.

Caught by: tests/desk_acc/text_preview.lua

Bump version to v1.5 (final)

Bump version to 1.5-beta1

Bump version to 1.5-alpha5

Bump verson to 1.5-alpha4

Bump verson to 1.5-alpha3

Bump verson to 1.5-alpha2