Allow --app flag to be passed on mix new

  Allows path to not follow app name conventions
Docs: ensure docs for Dict use full variable names

The following variable switches have been made:

 * `d` has been changed to `dict`
 * `a` has been changed to `dict1`
 * `b` has been changed to `dict2`
 * `d1` has been changed to `dict1`
 * `d2` has been changed to `dict2`

 This fixes #2574
Merge pull request #2575 from Gazler/docs/dict

Docs: ensure docs for Dict use full variable names
Docs: change Dict.merge description to read more naturally

Previously there was an additional "dict" - this is as a result of it
previously saying "dict `a`"
Merge pull request #2576 from Gazler/docs/dict

Docs: change Dict.merge description to read more naturally
allow lowercase http(s)_proxy env var
Parse unary/binary operators regardless of number of spaces

closes #2534.
Added @doc false to handle call
Merge pull request #2582 from tomkadwill/added-doc-false

Added @doc false to handle_call functions
Merge pull request #2581 from mururu/parse-space

Parse unary/binary operators regardless of number of spaces
Merge pull request #2580 from Joe-noh/lowercase-http-s-proxy

[MIX] allow lowercase http(s)_proxy env var
Merge pull request #2556 from patrickgombert/master

Allow --app flag to be passed on mix new
use os.timestamp for setting random seed in doc examples
small evaluator refactoring
Update mix's mix.exs to fix escript.build
Update Elixir's mix.exs to fix escript.build
Merge pull request #2590 from MSch/fix-mix-escript

Fix mix escript
Merge pull request #2586 from jquadrin/patch-1

small IEx evaluator refactoring
Merge pull request #2585 from herenowcoder/enum-docs

use os.timestamp for setting random seed in doc examples