Make fixture test templates "pretty"

[jasmith-hs]

Allows fixture templates to be separated by newlines for easier readability.
Use \ to escape the newlines similar to escaping in bash scripts.

Certainly this:

{% do __temp_import_alias_902286926__.update({'import_resource_path': 'macro-and-set.jinja'}) %}\
{% endfor %}\
{% set simple = __temp_import_alias_902286926__ %}\
{% set current_path = '' %}\
{% enddo %}\
simple.foo: {% set deferred_import_resource_path = 'macro-and-set.jinja' %}\
{% macro simple.foo() %}\
Hello {{ myname }}\
{% endmacro %}\
{% set deferred_import_resource_path = null %}\
{{ simple.foo() }}

Is easier to read than this:

{% do __temp_import_alias_902286926__.update({'import_resource_path': 'macro-and-set.jinja'}) %}{% endfor %}{% set simple = __temp_import_alias_902286926__ %}{% set current_path = '' %}{% enddo %}simple.foo: {% set deferred_import_resource_path = 'macro-and-set.jinja' %}{% macro simple.foo() %}Hello {{ myname }}{% endmacro %}{% set deferred_import_resource_path = null %}{{ simple.foo() }}

The actual output may not have any newlines in it, but for writing, understanding, and debugging test failures, splitting up the jinjava nodes with newlines is very helpful. And the \ denotes that the pretty spacing is not actually part of the output.