"Out of source" buids and parallel platforms

New features:

• Configurable location of build artifacts
• Support overriding of binaryTag per invocation, closes #21 (closed)

Fixes:

• Fix setting of empty string value with config.py
• Fix stats script (when LbEnv is not sourced)

Internal changes:

• Set project version for the super project
• Update distcc server instructions
• VSCode: trying to support cmake with monobuild