Query Engine Refactor

[JabobKrauskopf]

Completely remove the old query engine and write a new one from scratch with added funcitonality.

• Define query engine interface #170
• Rewrite Query Engine in Rust #171
• Rewrite rust to python bindings #172
• Rewrite python query engine wrappers #228

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After the above issues the first draft of the query engine will be merged.

• Fix bugs
  • fix: comparison operations now correctly evaluate operand #233
• Usability improvemets (sorted by importance & difficulty)
  • Replace node.incoming_edges() and node.outgoing_edges() with node.edges(EdgeDirection) #244
  • Add .exclude(query) operand #242
  • Allow SingleAttributeOperand in def attribute(...) and def has_attribute(...)
  • Try to make value changing operations not in place. see code example 1
  • Try to implement count() on NodeOperand and EdgeOperand
• Add docstrings
• Write tests
• Try to refactor TODOs in code
• Improve performance

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code example 1

a = edge.attribute("amount").min()
b = a.add(5)

After this, a should represent e.g. 5 and b should then represent 10