implemented webview instead of browser intent

this reverts #485, fixes #451
some minor refactoring regarding urls done too
Fix incorrect text in Dialogue for "When..." bricks.

changed "Delete Brick" to "Delete Script" in the context menu and "Delete this brick?" to "Delete this script?" in the ensuing dialog for "When..." bricks.

- added strings for dialogue in strings.xml

- added the setting of the strings in the BrickAdapter (onClickListener)

- refactored Tests for "When..." bricks
done
fixed copy sprite bug
usage counter for look image increments now