Log Message:
Update to 5.7

Upstream changes:
2019-01-24 : Release 5.7
    Bug fix release with a few user visible additions.
2018-01-24  dana  <dana@dana.is>

        * unposted: Config/version.mk, README: Update for 5.7

2018-01-23  dana  <dana@dana.is>

        * 44012: Test/X04zlehighlight.ztst: Fix spurious test failures
        on OpenBSD

2019-01-23  Mikael Magnusson  <mikachu@gmail.com>

        * 44011: Doc/Zsh/zle.yo, Src/prompt.c, Test/X04zlehighlight.ztst:
        Only use fg_start_code for non-truecolor