Added Module#module_exec and Module#class_exec

Module#module_exec
- does not add defined methods to other classes
- defines method in the receiver's scope
- evaluates a given block in the context of self
- raises an LocalJumpError when no block is given

Module#class_exec
- does not add defined methods to other classes
- defines method in the receiver's scope
- evaluates a given block in the context of self
- raises an LocalJumpError when no block is given
Fixnum#equal? should be alias to Fixnum#==

Also untaged passing specs:

Module#module_exec
- passes arguments to the block

Module#class_exec
- passes arguments to the block
Implemented Module#new

Fixes specs:

Module.new
- creates a new Module and passes it to the provided block
- evaluates a passed block in the context of the module
Remove extra method definition
Moved logic to #initialize
Merge branch 'master' into pr/666

Conflicts:
	spec/tags/core/module/new_tags.txt
Some style nits.