#62 temporary workaround
Initial limit support (doesn't work properly)
XML support
stub
useless commitment
Limit partially implemented (see #65)
Merge branch 'master' of https://github.com/bvanr/math-dragon into work
#55 fix
Unused imports removed
#55 and #65 fix
Setters and some javadoc implemented
Another constructor and some javadoc implemented
#60 fix for currently implemented trigonometric functions
Javadoc for toOpFunction(AST) and some commented stuff removed
Some minor readability improvements
+ Added default constructor to MathOperationLimit
+ Added support for ln() in ModelHelper
- Removed the possibility for MathOperation to have null as a child

Signed-off-by: Mark Kamsma <mark@markkamsma.nl>