In the templates and the /config (JSON) the usage of the 'brand.*' name
space is replaced by 'searx.get_setting' function.

- new_issue_url          --> get_setting('brand.new_issue_url')
- brand.GIT_URL          --> get_setting('brand.git_url')
- brand.PUBLIC_INSTANCES --> get_setting('brand.public_instances')
- brand.DOCS_URL         --> get_setting('brand.docs_url')
- brand.ISSUE_URL        --> get_setting('brand.issue_url')
- brand.CONTACT_URL      --> get_setting('general.contact_url', '')

The macro 'new_issue' from searx/templates/*/messages/no_results.html
is now imported with context::

    {% from '__common__/new_issue.html' import new_issue with context %}

To get *public instances URL* from context's 'get_setting()' function::

    get_setting('brand.public_instances','')

Macro's prototype does no longer need the 'new_issue_url' argument and has been
changed to::

    macro new_issue(engine_name, engine_reliability)

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Hide textarea from github issue form::

    ./__common__/new_issue.html:6:    <textarea name="body" style="display: none;">{{- '' -}}

BTW: fix indentation.

Reported-by: https://github.com/searxng/searxng/issues/57
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

Inline styles are blocked by default with Content Security Policy (CSP).  Move
the inline styles from 'new_issue.html' to::

    searx/static/themes/__common__/less/new_issue.less

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

allow to submit a github issue including the technical details
(exceptions, errors, warning, checker result)