fixes JOO-83
Package-level variable not initialized by method calls
http://jangaroo.myjetbrains.com/youtrack/issue/JOO-83

Method calls on other compilation units were always mistaken
for static methods, suppressing the eary initialization.
Now, the compiler distinguishes calls on classes (=>static
method: do not initialize, runtime will take care!)
and calls on variables (=>non-static method: initialize!).