v1.2.0: Abstract builder and version fix

The version in the pom.xml was fixed and the Builder class is now called DefaultBuilder while extending a new abstract Builder class.

v1.1.0: Add Getters for TokenReaders, Operators and ValueReaders to Builder

The Builder class now exposes the currently set TokenReaders, Operators and ValueReaders through getter methods.
This should allow you to extend the Builder to use the createDefault() method without having to re-implement all the default tokens.

v1.0.0: First release

This marks the first release of the ExpressionParser library!