add basic documentation.
do not read copyright file if path is blank.

If the `copyright_file` variable is left blank, the `LicenseDialog` will
not attempt to read any copyright file and will not populate the
`ComponentList` tree with project component information.

Projects will no longer push warnings if the `copyright_file` variable
is left as a blank string, which is now default.  However, the warnings
will still occur if the user specifies a file path which does not exist,
or if the project finds a copyright file which is not formatted

In order to make this change work, the `onready` keywords have been
removed from the `project_name` and `copyright_file` variable
remove _label_text variable.

The more I think about it, the more having a whole separate variable and
functions which modify the text of a label seemed wasteful and
unnecessary.  This commit removes that variable and repurposes the
`set_label_text` function as a shortcut.

Because this variable is no longer being used to modify the text of the
label, the script for the `LicenseDialog` no longer needs to update
editor properties, so the `tool` keyword has been removed.
use vars to reduce get_node calls.

The script for the LicenseDialog node has been modified to only use
`get_node` once for each node within the LicenseDialog.  This is done
for the benefit of programmers who are optimizing their source code.  It
also makes the script more concise.
split GUiLD & Sample Project into 2 components.

The COPYRIGHT.txt file now treats GUiLD and the included sample project
as two separate components, to make it more clear that the sample
project is optional and not a part of GUiLD itself.

This commit also renames the project to Godot Unofficial License Dialog,
because the old name was stupid.
add sample project & export preset.

Add the example project which demonstrates how the LicenseDialog node
can be used, and an export preset which demonstrates how to include the
COPYRIGHT.txt file in exported binary files.
do initial commit.

This repository will be initialized with the first "release" versions of
the LicenseDialog node and its script, and the sample COPYRIGHT.txt