sync tigris and euphrates version options

[mcandre]

• Declare the version number string export TIGRIS_VERSION=0.0.1 in lib/version.sh, as a primary source of truth for this information.
• Have tigris and euphrates load this shell configuration on launch. The location of lib should be inferred in terms of <script's own directory>/../lib
• Add CLI -v flags to tigris and euphrates to emit the version and terminate clean.

We may need to move the AppleScript code out of the tigris executable into its own lib/tigris.applescript file, as a way to simplify the logic.

[mcandre]

Added to euphrates.

This provides a basic version identification system.

Later we can refactor tigris, to reduce risk of the tigris executable contents in rare cases getting out of sync with euphrates.