Remove `L99_HOME` and `L99_SETUP` env vars

[bburns]

As for the L99_HOME variable, it looks like it's hardly used, so we could remove it eventually - I had been in the midst of translating from './l99 foo' usage to 'l99 foo' -

remove L99_SETUP var Where can I find what is the L99_SETUP env var used for? What should be its value? In shell/install/cli, is only initialised, but no value is defined I think that's not actually used anymore - it stores the current setup in a .l99_setup file instead. Adding to list.