Adding Out of Source Build Example

doc/examples/out-of-source-build/elements/base.bst

doc/examples/out-of-source-build/elements/base/alpine.bst

doc/examples/out-of-source-build/elements/sourceroot.bst

doc/examples/out-of-source-build/elements/subfolder.bst

doc/examples/out-of-source-build/files/hello/README

...amples/out-of-source-build/files/hello/src/CMakeLists.txt

...s/out-of-source-build/files/hello/src/main/CMakeLists.txt

doc/examples/out-of-source-build/files/hello/src/main/main.c

doc/examples/out-of-source-build/project.conf

doc/sessions/out-of-source-build.run

doc/source/examples/out-of-source-build.rst

...ource/sessions-stored/out-of-source-build-build-main.html

doc/source/sessions-stored/out-of-source-build-build.html

...ource/sessions-stored/out-of-source-build-shell-main.html

doc/source/sessions-stored/out-of-source-build-shell.html

...e/sessions-stored/out-of-source-build-show-variables.html

doc/source/using_examples.rst

tests/examples/out-of-source.py