added checking for help anim/text files in different locations

added checking for help anim/text files in different locations

Instead of only checking for help anim/text files in the current level
set directory, these files are now also checked for

- in the configured graphics set directory
- in the path from the current to the topmost level set directory

This adds some flexibility and optimization for adding help anim/text
files for large level collections that all use the same help files.