Need to fix error message for well overflow when writing Echo picklist

[mkapasiawala]

Currently, if a well has a volume over the maximum specified volume, then then an error message is thrown and a picklist cannot be written. This should be modified so that the the volume cannot be over the maximum volume plus some tolerance (0.1%?). Error messages seem inappropriate for going 1 nL over in a 10000 nL reaction. The Echo is only capable of dispensing reagents in 25 nL increments, and sometimes this makes it so that a well is slightly over the desired volume, which is generally okay experimentally.