Simple demos of how to build a JavaCC parser using maven.

Provides several simplified unit parsing grammars based on the 
JSR 275 grammar found at https://github.com/unitsofmeasurement/jsr-275/tree/master/src/main/javacc/javax/measure/unit/format

Note that these are demos and have not been tested.

UnitParserNoMix.jj - this is the base parser for the others below. This is 
a working version of the original parser with the 'mix' construct 
deleted. In the documentation, a mix expression is 
<mix_expr>	:=	<add_expr> ( ":" <add_expr> )*. It is not clear
from the code what this should be - the second add_expr seems to 
be ignored. 

UnitParserExp.jj - a unit parser that replaces the exponential
construct e^{} with a function exp(). This means that 'e' is no 
longer a reserved character.

UnitParserMinimal.jj - a unit parser that does not support:
 - exponentiation, other than units being exponentiated by an integer, 
 - logarithms
 - addition

Some simple demos of these parsers being used are given in TestParser.java.


Also provided is a simple class demonstrating how to add alises to
EBNFUnitFormat.