Ability to assign PB functions' expressions to constants

[Psychophanta]

Currently can be done this:
#ff1=1/4.5*3+42-23|7~57!25%24
which means that operands' expressions are evaluated at compile time when assigning to a constant.

But this can't be done:
#ff1=ACos(-1)
which means that native PB functions (using constants only, not variables, of course) are not evaluated at compile time when assigning to a constant.

Allowing this should be good

[#NULL]

that would be nice indeed.

[hellhound66]

Removed.