Hint reference parsing

[cicr99]

Fix #548

The changes in the grammar:

• allow more complex expression to be parsed. For example, more than only two terms to be operated
• include missing cases such as:
  • a simple number as the expression to be casted
  • double dereference inside the expression
• parse the numbers inside the expressions as a string as to allow numbers bigger than 64 bits

[Sh0g0-1758]

LGTM