Yuras authored Aug 29, 2015 and Ben Gamari committed Aug 29, 2015

Now identifiers can start with a package key, which is a hash, so they
may also start with a digit. Identifiers always appear at the beginning
of a line, and numbers never appear here, soit's safe to allow
identifiers to start with a digit.

Test Plan: `concprog002` passes under `threaded2_hT` way

Reviewers: austin, bgamari, thomie

Reviewed By: austin, bgamari, thomie

Differential Revision: https://phabricator.haskell.org/D1175

GHC Trac Issues: #10661