Add InputOp and OutputOp interfaces

See issue #26.
Make Function extend InputOp and OutputOp

See issue #26.
Merge pull request #27 from imagej/input-output-ifaces

Merged. Thanks again @ctrueden
Updated Velocity Version

The new version (1.7) provides some nifty features like foreach.
generate.groovy: Added parsing of values as Maps or Lists

This grants loads of possibilities in the velocity templates, which
support loops.
Added template and list for arithmetic ops interfaces.
Added template and list for RealType implementations of arithmetic ops interfaces.
Template tests now test the Lists and Maps aswell.
Enhancements to .list parsing

Now supports Lists and Maps which can improve readability of .list
Improved template of template for RealType implementations of unary arithmetic interfaces

This commit adds possibility to define custom initialization of members,
javadoc is now received as a single line string without *, /* or */,
additional authors are now defined in a list,
imports are defined as lists in the .list from now on, import keyword is nolonger
needed in the .list.
Additional constructor code can be added in the .list aswell.


Signed-off-by: Jonathan <squareys@googlemail.com>
Arithmeticreal_implementations.list now uses new template

Improved readability alot, also gotten rid of loads of redundant code.
Added test for escaped values in list.