Upgrade the VDMUnit library with VDM-SL support

[lausdahl]

It would be nice with VDM-SL support for testing like VDMUnit.

It could work by using modules ending with MyTest and then scanning for operations starting with test like in VDMUnit:

It could work with a test running like:

module TestRunner
exports all
definitions 

operations 
run : ()==>()
run()== is not yet specified;

end TestRunner

then if TestRunner.run() is executed then it will run the following operations for this model:

module MyTest
operations 
test: ()==>()
test()==(IO`println("running my test now."); exit; IO`println("continuing."));

test1: ()==>()
test1()==(IO`println("running my test now."); skip; IO`println("continuing."));

test2: ()==>()
test2()==(IO`println("running my test now."); exit; IO`println("continuing."));
end MyTest

module My2Test
operations 
test: ()==>()
test()==(IO`println("running my test now2."); skip; IO`println("continuing2."));

test1: ()==>()
test1()==(IO`println("running my test now."); skip; IO`println("continuing."));

test2: ()==>()
test2()==(IO`println("running my test now."); exit; IO`println("continuing."));

end My2Test

• MyTest: test, test1, test2 where the first one will fail
• My2Test: test, test1, test2 where the last one will fail