3.0.0: New units

This release contains some typo's. Please use 3.0.1 instead.

Breaking change:

• The symbol of Ampère was wrong. In previous version, it was "amp". It is now correctly "A".

Added some extra metric prefixes:

• milliampere (mA)
• micronewton (µN)
• picometer (pm)
• nanometer (nm)
• micrometer (µm)
• deciliter (dL)
• hectoliter (hL)