Fix many bugs
Add assign and progn special forms.
Implement tests
Add a test case to progn test suite.
Merge branch 'lispization' of https://github.com/dakusui/petronia into
lispization

Conflicts:
	src/main/java/com/github/dakusui/arbitris/eval/BaseForm.java
	src/main/java/com/github/dakusui/arbitris/eval/pred/BasePredicate.java
	src/test/java/com/github/dakusui/petronia/NumericFuncTest.java