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>

.github/workflows/main.yml

@@ -0,0 +1,64 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Run tests
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Update rustup
+      run: rustup self update
+    - name: Install Rust
+      run: |
+        rustup set profile minimal
+        rustup toolchain install 1.41.0 -c rust-docs
+        rustup default 1.41.0
+    - name: Install mdbook
+      run: |
+        mkdir bin
+        curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.3.7/mdbook-v0.3.7-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+        echo "##[add-path]$(pwd)/bin"
+    - name: Report versions
+      run: |
+        rustup --version
+        rustc -Vv
+        mdbook --version
+    - name: Run tests
+      run: mdbook test
+  lint:
+    name: Run lints
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Update rustup
+      run: rustup self update
+    - name: Install Rust
+      run: |
+        rustup set profile minimal
+        rustup toolchain install nightly -c rust-docs
+        rustup default nightly
+    - name: Install mdbook
+      run: |
+        mkdir bin
+        curl -sSL https://github.com/rust-lang/mdBook/releases/download/v0.3.7/mdbook-v0.3.7-x86_64-unknown-linux-gnu.tar.gz | tar -xz --directory=bin
+        echo "##[add-path]$(pwd)/bin"
+    - name: Report versions
+      run: |
+        rustup --version
+        rustc -Vv
+        mdbook --version
+    - name: Spellcheck
+      run: bash ci/spellcheck.sh list
+    - name: Lint for local file paths
+      run: |
+        mdbook build
+        cargo run --bin lfp src
+    - name: Validate references
+      run: bash ci/validate.sh
+    - name: Check for broken links
+      run: |
+        curl -sSLo linkcheck.sh \
+          https://raw.githubusercontent.com/rust-lang/rust/master/src/tools/linkchecker/linkcheck.sh
+        # Cannot use --all here because of the generated redirect pages aren't available.
+        sh linkcheck.sh book