Support switch template instructions
A switch variable can have multiple values
Regression test for #249
Fix #249 (erlc regression)

The combination of changes to rebar_erlc_compiler, and the fact
that erl_first_files is inherited, caused a regression. To fix
that, ensure every project uses its own .rebar/erlcinfo. While at
it, fix the issue that erl_first_files entries were not included
when initializing the dep digraph.

Reported-by: Louis-Philippe Gauthier
Reported-by: Roland Karlsson

Thanks: Tuncer Ayaz
Merge pull request #195 from fgallaire/switch_template_instructions

Switch template instructions
Add gen_event template
Merge pull request #296 from runcom/add_gen_event_template

Add gen_event template
Merge pull request #285 from nevar/fix_inheritance

Fix #249 (erlc regression)