Tables creation from Exchange AST

[termoshtt]

Before creating tables automatically by espr as described in ARCHITECTURE.md, we must try to create them by hand to determine its specification.

TODO

• Create tables manually Create tables manually #15
• Convert Exchange AST to manually generated tables Deserialize tables using serde #22
  • Basic serde integration (for HEADER section) Deserialize STEP Record by serde #18
  • Nested record support serde::Deserializer for nested record #21
  • PlaceHolder for reference e.g. A((1.0, #11)) PlaceHolder for handling references in STEP Record #20
• Documents for tables submodule Iterator accecor for entities #24
• Generate tables definitions by espr
• Add about serde in ARCHITECTURE.md