stfl: refuse to load if interpreter lacks UTF-8 support
stfl: wrap stfl_create
stfl: map stfl_free
Revert "stfl: map stfl_free"

This reverts commit 3d5d1fc0bf45b352dd1c1641dd6ad956563bdede.
Revert "stfl: wrap stfl_create"

This reverts commit 6da6a2a980e50c85b184d85a5caafdc1c149c7f4.
stfl: create library initializer functions