(Beta) property upload, sms_send, multiple fixes

[Beta] new property type upload to replace custom_images and custom_attachments. It is still work in progress and the interface might change. Final documentation to be provided within the next few weeks.
added sms_send GraphQL mutation to work similarly to email_send and api_call_send

gracefully handle error when admin_* mutation was invoked with name, but without required physical_file_path
pos-cli logs sometimes included unnecessary internal error message
added model_name as a restricted property name
added graceful handling of a scenario of uploading a file with a name that's too long
added better handling of invalid regpexp in regex_matches filter
fix descriptions of multiple GraphQL mutations
fix documentation example of raw_escape_string filter
fix edge case scenario when integer is provided as a path name for the include tag
{% form %}{% endform %} was rendering nothing instead of the form HTML tag
fixed edge case scenario when invalid arguments were provided to precision argument in the time_diff filter
fixed edge case scenario when invalid arguments were provided to the format_number filter

Questions?