Validation checks for TOML profiles

[cerebis]

• TOML profile defintions are now checked for missing parameters. Users are warned when a parameter is undeclared, while sim3C will continue with defaults.
• Float precision has been standardised to 32bit. This is in consideration of PCG base integer RNG, which returns 32bit integers. This is relied upon in generating uniform RNG between [0..1] and thus their precision is also 32-bit. To avoid unforeseen issues when mixing 32 and 64 bit floats in expressions, I have opted to drop handling of PDFs and CDFs to 32 bit.
• some global references to methods have been removed for clarity. They did not improve performance.
• a version stamp parameter was added to the TOML profile definition. As there is currently only one version of the format, this simply tests for existence.