Complete

Adds autocompletion to iocsh.bash. Not a needed feature, but a nice one. There is probably lots of room for improvement, but it still is a bit nice as a first draft.

The autocomplete script is also sourced when you source setE3Env.bash, so the functionality is set to work as-is for users.

Some functionality:

• -l (cellMods path) will only autocomplete for directories
• -r will look at EPICS_BASE and E3_REQUIRE_VERSION and then only autocomplete to modules that are found there
• -c (which runs specified commands) autocompletes to a list of valid/plausible ioc shell commands.