Clamp before downcasting in float to i8 conversions

[Ngalstyan4]

Previously we were downcasting floats to the target type (e.g. int8_t), and then
clamping to [-100, 100] range. This means that e.g. 129 would be cast to -127 and
then converted to -100, in stead of becoming 100

The fix does clamping first, and then casts the resulting number
(which is guaranteed to be in range [-100, 100], due to clamping)
from source type to target int8_t. Given the clamping, this will never overflow.