Fix incorrect info in minirake's help message -- "-q" is the default, not "-v"

Conflicts:

	minirake
Fix #2259 .

Conflicts:

	src/kernel.c
instance method name use "#" instead of "." for assert
Add test for remove_instance_variable
Add 'Raise in rescue' test to exception.
correct comment; ref #2297
Correct comment in exception test.

Conflicts:

	test/t/exception.rb
Exception#exception fix test

Exception.exception is not call Exception#exception.
Test for Exception#exception should call Exception#exception method.
fix typo.