Make the settings screen redraw 50x faster

Arrow-key navigation took 435 ms per keypress, which reads as the whole console
reloading on every press - because it effectively was. The cost was forks: each
frame ran a command substitution per label for the value, the translation and
the rendered state, 54 subshells for eighteen rows.

The frame is now assembled in memory and written once. Translations, the split
specs and the terminfo clear string are resolved before the loop; values are
re-read only after something actually changes, not on cursor movement. Helpers
on that path assign to a variable instead of printing, since printing is what
forced the substitution.

Measured on the same machine: 435 ms -> 7.5 ms per keypress.

Makefile

@@ -8,7 +8,7 @@
 # Overridable so a packager can pass the version it is actually building
 # (`make VERSION=$pkgver`). The literal below is the fallback for builds
 # straight from a checkout, and is what a release tag has to carry.
-VERSION      ?= 1.1.0
+VERSION      ?= 1.1.1
 
 PREFIX       ?= /usr
 DESTDIR      ?=