On some systems, libraries are installed to `/lib64`, whereas they are installed
to `/lib` on others. We add a simple test to select the right directory.

Note that this might not cover all systems, but they are the most two common ones
that we encountered so far.

Update the CMake minimum required version and use the FetchContent module
to retrieve the Yoda sources directly from GitHub if the YODA_ROOT
environment variable is empty.

## Technical Description

Provides (de)serialization capabilities to json files. 

## Testing

Was tested with the set of stencils provided in the code gen tests in the sense that code gen from DSL and codegen with an intermediary serialization and de-serialization step produce the same code. Proper testing for (de)serilization and using (de)serialization to test the code gen will be introduced in a separate PR.  

## Dependencies

Depends on [Pull Request 154](https://github.com/MeteoSwiss-APN/gtclang/pull/154) in the gtclang repo

Due to changes in SIR and AST structures these tests were failing.

* adding AST component

and aliases and prefixes

* Fix function referenced from gtclang

Moved getFieldFromStencilAST to AST component.

* Removing sir::Field reference from BoundaryConditionDeclStmt

Substituting with field name (string).

* Move StencilCall to AST

As it contains information common to both SIR and IIR

* Applying review suggestions

* Applying suggestions

We remove all the backwards dependencies from the Optimizer Context to the Dawn-Compiler. This is part of cleaning up all unwanted (circular) dependencies between modules

Remove `SIRSerializer.h` and `SIRSerializer.cpp` which exist already in Serialization.

## Technical Description

This fixes the issues with the namespaces used in generated code. Namespaces like "cuda" or "gridtools" should be used only by cuda and gridtools themselves. Hence the namespaces in all code generated now have the suffix "_dawn" added
#### Resolves

[Issue 144](https://github.com/MeteoSwiss-APN/gtclang/issues/144) reported in the gtclang repo
## Dependencies

This PR is independent.

Disable python if protobuf doesn't have python

* adding AST component and moving into it classes and functions that are in SIR/AST*.h header files

* adding aliases in SIR/AST*.h and IIR/AST*.h header files

* prefixing references to AST classes in the whole codebase with the correct namespace (sir:: or iir::)

* Applying review suggestions

Restores performance to before this bug was introduced

PEP8 formatting for dawn examples

We remove all the backwards dependencies from the Seriaizer to the Optimizer. This is part of cleaning up all unwanted (circular) dependencies between modules

Silence warnings of external headers (json, tinyformat) by including them with `-isystem`. This is achieved by adding an extra include directory for the external folder.

Fix warnings for clang 8.

We remove all the backwards dependencies from Code-Gen to the Optimizer. This is part of cleaning up all unwanted (circular) dependencies between modules

Adds minimal a build-tree CMake configuration for dawn. The configuration is good enough for GTClang.

Fixes the path in the jenkins build script to actually run the python tests. Also the build-script exits on error now.

Closes #77

Moves the axis computation to the stencil-level so we're not computing illegal states

Creates an option to install dawn in a specific place in the jenkins env

Changes the default behavior of the bundle to not run the python examples as the default is not to install the required python modules.

There was a default constructor setting it's const-ptr to a nullptr and should therefore never be used. This makes them private. (Solution by @Stagno)

Update to clang-format 6.0 and a reformatting of the repo