initial commit: The OrbTK book source tree

All files have a strong relation to the book sources of the
rust-lang project itself. This may help to lower the burden
for intrested people to get involved in OrbTK as well as
reuse workflow habits.

* LICENSE-MIT: The projekt licensing terms
* README.md: Github frontpage
* CONTIRBUTING.md: Advises on howto help improving the book
* style-guide.md: Advises on howto improve the readability of
  generated prose and code.
* tools: layout helper scripts and rust-code
* ci: continius integration helper scripts
* .gitattributes: set git default behaviours
* .gitignore: keep source tree sane
* Cargo.toml: package dependencies
* rustfmt.toml: formatting rules for rust code
* book.toml: mdBook dependencies

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

book.toml

@@ -0,0 +1,21 @@
+[book]
+title = "The Orbital Widget Toolkit"
+description = "The Orbital Widget Toolkit is a multi platform toolkit, that enables you to build scalable user interfaces. All components are devoloped with the programming language Rust."
+authors = ["Florian Blasius, with Contributions from the Rust Community"]
+language = "en"
+
+[build]
+create-missing = false
+
+[output.html]
+additional-css = ["theme/2020-edition.css"]
+git-repository-url = "https://github.com/redox-os/orbtk/book"
+
+[output.linkcheck]
+# Should we check links on the internet? Enabling this option adds a
+# non-negligible performance impact
+follow-web-links = false
+
+# Are we allowed to link to files outside of the book's root directory? This
+# may help prevent linking to sensitive files (e.g. "../../../../etc/shadow")
+traverse-parent-directories = false