object(foo), prog(), 'constant' and class foo {} implemented

Rev: src/ChangeLog:1.18
Rev: src/builtin_functions.c:1.9
Rev: src/builtin_functions.h:1.2
Rev: src/docode.c:1.3
Rev: src/interpret.c:1.8
Rev: src/language.yacc:1.6
Rev: src/lex.c:1.6
Rev: src/object.c:1.3
Rev: src/object.h:1.3
Rev: src/pike_types.c:1.5
Rev: src/program.c:1.4
Rev: src/program.h:1.2
Rev: src/testsuite.in:1.6