At the follow link
Android Dev Guide
is write:
Library projects cannot include raw assets The tools do not support the use of raw asset files (saved in t
Intellij Idea (and android studio as it's based on intellij) has a feature that let you include the asset files of the library module to application module, I don't know about other environment.
Go to project structure in file menu, then facets, choose application module, in compiler tab check "include assets from dependencies to the into APK" checkbox.
As intellij is far better than Eclipse, I think migrating is reasonable.
EDIT:
Asset and manifest merging are fully supported in android studio.