Sci Calc: Functions don't produce correct intermediate values

[inexorabletash]

This works as expected:

1 + 2 SIN = - yields 1 + SIN(2) = 1.909...

This doesn't:

1 SIN + 2 = - should yield SIN(1) + 2 = 2.841

... but actually yields 2 + whatever the previous result was (might be 0 so 2, etc)

The root cause is that farg is never updated after the function is used:

In the first example:

• 1 FAC = 1
• + farg = ROUND(FAC); last_op = +
• 2 FAC = 2
• SIN FAC = SIN(FAC)
• = FAC = farg + FAC

In the second:

• 1 FAC = 1
• SIN FAC = SIN(FAC)
• + last_op = +
• 2 FAC = 2
• = FAC = farg + FAC