Added SetFixedTest
SinkTestCase: add javadoc
SinkTestCase: fix javadoc
Added misc legal/illegal config tests
Added DesignSpaceCachingTest
Added CodeMappingCachingTest
build.xml: tests do not fork

This change is a speed tweak.
Added AccessorTester and CustomAccessorTester
Added DesignCachingTest
CodeMappingCfg: add semi-unique IDs

The builder avoids caching issues by generating default IDs using a
counter, just like DesignSpaceCfg.Builder.
MappingCfg: add param(...)

It's now possible to list multiple parameters when setting the ID of
the mapping to that of a parameter. This allows absolute IDs to be
generated automatically for nested parameters.