docu: some notes on how to build using CMake

Author: torbjoernk

doc/source/installing.md

@@ -0,0 +1,47 @@
+# Building and Installing
+
+## Prerequesites
+
+* a recent C++ compiler, which supports most of the C++11 features
+* the [CMake](http://cmake.org/) build tool
+
+
+## Obtaining the Sources
+
+Just use _Git_ to clone the repository.
+
+
+## Building
+
+1. create a directory for out-of-source builds (usually, people are creative and name it `build`) in the source tree
+2. decide on what you want to build
+   
+   By default everythin gets build, i.e. tests and examples.
+   
+   To deactive the tests pass `-Dpfasst_BUILD_TESTS=OFF` to the _CMake_ command line.
+   
+   To deactive the examples, pass `-Dpfasst_BUILD_EXAMPLES=OFF` to the _CMake_ command line.
+   
+   If you are not on a _Darvin_ system (i.e. MacOS, OSX, ...) and you are using _Clang_ as the
+   compiler, you want to deactive the use of LLVM's libc++ by passing `-Dpfasst_DISABLE_LIBCXX=ON`
+   to the _CMake_ command line.
+   
+   In the end, for a build with _Clang_ on a Linux system without the examples, the call to _CMake_
+   looks like:
+   
+       cmake -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -Dpfasst_DISABLE_LIBCXX=ON -Dpfasst_BUILD_EXAMPLES=OFF ..
+
+   As the [Google Testing] and [Mocking Framework] are required for the unit tests, those are automatically
+   downloaded and build.
+   
+   In case, you enable the examples, [FFTW3] gets downloaded and build as well.
+3. run the unit tests (if unit tests have been built)
+
+       make test
+4. run the examples (if those have been built). e.g.:
+
+       ./examples/advection
+
+[Google Testing]: https://code.google.com/p/googletest/
+[Mocking Framework]: https://code.google.com/p/googlemock/
+[FFTW3]: http://fftw.org/