Can't enter fractional speeds in Actions/Change Speed

#### Issue details
I'd like to be able to tell my mower to change from 1 to 1.5 m/s using Mission Planner. But I can't since that entry box seems to limit to only integers., forcing me to decide between 1 and 2 m/sec.

#### Version
1.3.7314_23103

Start in the Mission Planner UI handling for Actions/Change Speed and inspect the entry box's validation for the reported version. Done means accepting a fractional speed such as 1.5 m/s instead of restricting the value to integers; verify the resulting action uses the fractional value.

Written by the indexing model from the issue text.