Use xml lib to produce <dependencies/>.

(Instead of string utils)
Use XML lib instead of string templating.

Inline the rest of the pom.xml into code.
Use "where" instead of "do ... let"
Null pointer primitive
Null pointer FFI test
Add ECA to contributors
Added simple benchmark system
Prune case trees properly on optimised Nat

x!-1 is treated as a special case in argument projection, where x is
assumed to be a Big Integer and has 1 subtracted from it. Case trees
where only a single constant or successor are left are now collapsed.
Merge pull request #589 from LeifW/xml_lib

Use an XML lib to produce the pom.xml, instead of string templating on a file.
Merge pull request #591 from eamsden/NullPtr

Add null pointer primitive and test for C codegen