Fixed imports

Hi there, I've fixed up several imports in the code along the project.

Some imports were misplaced, like imported in files where there not needed and then imported where there needed by importing those files. There were also a lot of generic `import *`, which can lead to confusion and are not recommended because it overloads the namespace with a lot of unused stuff.

I've tried to do the imports properly, in the files where they were needed and avoiding to do global imports at all.