tuple: don't truncate float in :update()

Before the patch there were the rules:
* float +/- double = double
* double +/- double = double
* float +/- float = float

The rules were applied regardless of values. That led to a problem
when float + float exceeding maximal float value could fit into
double, but was stored as an infinity.

The patch makes so that if a floating point arithmetic operation
result fits into float, it is stored as float. Otherwise as
double. Regardless of initial types.

This alongside saves some memory for cases when doubles can be
stored as floats, and therefore takes 4 less bytes. Although
these cases are rare, because any not integer value stored in a
double may have a long garbage tail in its fraction.

Closes #4701

(cherry picked from commit fef4fdfc)