Add unicodeit-repl crate that copies output to the clipboard

The new REPL crate makes it more convenient to paste unicode math in whatever other application you are using.

Added

• Release cross-compiled binaries for Windows with the GNU toolchain (vwvvvzzq)
• Add support for the \dots latex command (be63097)
  • This is not in the upstream unicodeit project, creating further divergence from upstream

Fixes

• Use bare file names in released checksum files (zxxyxqtm)