Serialize needs to be optimized

[marsve666]

Each time stringToUnit is called, the string-to-unit map gets rebuilt with a lowercase key. When parsing a lot of propertyvaluesets, it adds up and becomes slow. Possible solution, the caller have responsibility of giving the unit map in with lower case keys.

Slow part

[jonaskello]

Yes, we could just use the passed map without converting it to lowercase. Then it is the responsibility of the caller to keep have correct case in the map.

[jonaskello]

Since this will require a breaking change we might as well consider doing more than just removing the lowercase call. Perhaps we can do one of these:

(1) Remove the Serialize module and the 4 functions in it (serialize/deserialize unit and amount) (2) Move the functions for serialize/deserialize into the Unit and Amount modules and remove the Serialize mdoule (3) Keep the Serialize module and change the implementation only

[jonaskello]

@marsve666 Seems there are no strong opinions on this so perhaps the simplest way forward is to just keep the Serialize module the same in order to minimize breaking changes.

[jonaskello]

Fixed by #49