Simplify block generation

[mrp089]

Current situation

Closes #70 and #71: Simplifies block generation and introduces more error checking.

Release Notes

Major structure:

• Model.cpp: block_factory_map replaces switch case statement to generate new blocks
• Introduced InputParameter struct to store properties of input parameters (name, array?, optional?, number?, default value)
• Set InputParameter, BlockType (e.g. blood_vessel), and BlockClass (e.g. closed_loop) in the constructor of all derived Block classes

Major in solve/SimulationParameters.cpp (the file formerly known as io/configreader.hpp):

• Functions get_param_scalar and get_param_vector return an error if the input parameter is not optional and doesn't exist
• New universal generate_block function to create a block, read its input parameters, and register block and parameters with Model
• Replaced all block-specific parameter setups with generate_block
• Broke load_simulation_params up into sub-functions and introduced more input-checking:
  • create_vessels
  • create_coupling
  • create_bounary_conditions
  • create_junctions
  • create_closed_loop

New error checks:

• Cases documented in Add checking for a valid JSON to the svzerodsolver application #70
• Are all (non-optional) input parameters for each block given?
• Are any unknown input parameters given?

Minor:

• Doxygen: Set WARN_AS_ERROR to FAIL_ON_WARNINGS. This runs the whole build and throws all warnings as errors. (YES fails after the first error, which is annoying for debugging).
• Split up ClosedLoopCoronaryBC into ClosedLoopCoronaryLeftBC and ClosedLoopCoronaryRightBC (replaces side input parameter)

Limitations:

• There are still places in SimulationParameters.cpp that are very block-specific (especially in create_coupling). These could be replaced in the future by using BlockType, BlockClass, or new Block attributes.
• Add/move more error checks to validate_input.

Documentation

I updated the Doxygen documentation. After merging this, we can create a section on creating new blocks in the developer guide (#66).

Testing

We have built ourselves a very nice CI framework! I worked myself through all the block and interface tests. I made the following changes to the input files:

• Removed empty vessels and junctions inputs as they are no longer required
• Removed side input parameter and renamed ClosedLoopCoronary blocks
• Removed unused input (unsteady in ClosedLoopRCR, ClosedLoopCoronary and C in BloodVesselJunction)

Code of Conduct & Contributing Guidelines

• I agree to follow the Code of Conduct and Contributing Guidelines.

[mrp089]

I added more input checks after talking to @richterjakob and edited the first comment accordingly.

[menon-karthik]

This looks really good @mrp089. Thanks for this much-needed work! I have a few minor comments.