Add more functions

[KaiVolland]

It seems like we are missing some functions to be able to cover more complex operations:

Boolean:

• 'all'
• 'any'
• 'not' -> inverts one argument
• 'equalTo'
• 'notEqualTo'
• 'like' --> covered by strMatches
• 'greaterThan'
• 'greaterThanOrEqualTo'
• 'lessThan'
• 'lessThanOrEqualTo'

Mathematical:

• 'add'
• 'sub'
• 'mul'
• 'div'

Unknow:

• 'switch' or 'case'
• 'coalesce'?