vilan 0.6.2

Two generic miscompiles fixed. A &mut T view resolving to bool through
a generic, and integer division / bitwise ops on i32/u32 through a generic,
silently did the wrong thing: the boolean write-through was a no-op, i32/u32
division skipped its truncation (7 / 2 came out 3.5), and a u32 shift used
the signed operator. Both were monomorphization-time classifications that dropped
their verdict for the native-JS types — concrete code and every other integer
width were already correct. Found by an audit after v0.6.1's &mut bool fix.

! guides you to convert errors. ! returns a failure as-is, so the error
types must match; when they don't, the compiler now points at the fix instead of
calling it unsupported — .map_err(…) to change a Result's error, .ok_or(err)
to turn an Option's None into one. Conversion stays explicit (no hidden
From behind the operator), by design.