List.replace_at
Merge pull request #1558 from sasa1977/list_replace_at

List.replace_at
Fix a bug in insert_at adding items to the wrong location with negative indexes
Add Enum.reduce/2 that sets initial value of acc to the first element of collection

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Conflicts:
	lib/elixir/lib/enum.ex
Refactor Enum.min/1 and Enum.max/1
Deprecate Enum.min/2 and Enum.max/2 in favor of Enum.min_by/2 and Enum.max_by/2
Update CHANGELOG
Make System.get_env/0 behave sanely.
Merge pull request #1562 from alexrp/master

Make System.get_env/0 behave sanely.
Fix warnings and update CHANGELOG
Clean up Dict interface
Fixed doc typos in List
Fixed doc typos in Enum
Merge pull request #1567 from jwarwick/doc_typos

Fixed doc typos in List and Enum
Allow iex to --remsh into an Erlang node that has IEx
Support --detached and --hidden options
Slight clean up on dict_test.exs
Improve OptionParser switch validation

This adds a third element to the tuple returned from OptionParser.parse/2 when the value for an option doesn't match its switch type.
Use list concatenation operator instead of function
Add documentation for invalid switches