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 setlocal/endlocal to prevent polluting user's environment
Use start to spawn werl without lingering cmd window
Suppress "dumb terminal" warning
Add new --werl option