Not every system under test can be run with long names, and this makes
rebar's common_test support useless in those environments, as it
currently uses long names (test@hostname.domain) by default, without
recourse to change them.

This patch adds support for a {ct_use_short_names, boolean()} config
variable, which allows the user to specify whether short or long names
are required.

Newly added syntax:

{deps, [ {<depname>, ".*", {rsync, "<rsync_url>"}}, ... ]}

Where rsync_url is any URL accepted by the rsync command.

{port_specs, [{".*", "priv/foo.so", ["c_src/foo.c"], [{env, []}]}]}.

Use correct ERL_LIBS separator on Windows.

The custom queries are configured in rebar.config via the tuple
{xref_queries, [{query(), query_result()},...]}.  The implementation
passes the query() string to xref:q and compares the return value with
query_result(). It will result in an error if they do not match.

The following configuration, for example, is the same as running the
xref check undefined_function_calls. It additionally filters
ejabberd_logger:*_msg/4 from the result as these functions are generated
on execution by ejabberd and not available at compile time.

{xref_queries, [{"(XC - UC) || (XU - X - B -
                 (\"ejabberd_logger\":\".*_msg\"/\"4\"))",[]}]}.

This patch also modifies the build process of this package by running a
custom query instead of doing a diff against a static xref_warning file.

This change adds the ability to use alternate urls for downloading
dependencies. To make use of alternate urls run:
rebar get-deps alt_urls=true

If you have dir with many erlang app, then you can simple write
{sub_dirs, ["some_dir/*"]}. Rebar will make operation on subdirs of
dir "some_dir".

The latest version of erlydtl requires that custom tag modules be in
the path when templates are compiled. Without this change rebar silently
exits when using the custom_tags_modules option.

Automatically include modules with callback attributes in
erl_first_files.

* consolidate options
 * add support for building executables