Get some diagnostic info on why the Idris REPL refuses your connection.

Or get an alert someone's trying to hack you, whatever.
Why "do" when you can "<$>"?
Remove calls to "error". Fixes #607.
Make --ideslave imply --nocolour
Merge pull request #620 from david-christiansen/issue/607

Remove uses of error from ideslave and fix colouring
Merge pull request #619 from LeifW/diagnostic_on_repl_network_deny

Diagnostic on repl network deny
Add floating point primitives to LLVM backend

* implement floating point primitives in LLVM codegen
* prepare for moving some float constants and code in Prelude
  and base
* add a test for the presence of floating point primitives
  in a given backend