Tutorial fixes

Some small fixes for stuff found when translating the tutorials:

• quickies.xml used Windows-style CRLF line endings. Change this to use LF as is used by all other files in src. Without this, any changes in that file showed a ^M at the end of changed line in git diffs.
• The submenu Clouds was replaced with Noise in gimp@47127014
• Minor fixes relating to spelling, whitespace etc.

v2: There is no more Use color from gradient checkbox. It is instead an option under Dynamics.