STLReader: Close the file when an error occurs

Change-Id: I38a189e6af609836a846d892050440e69473a9b7
STLReader: Fix error signaling when reading files

The RequestData return value of 0 means an error and make the actual
reader implementations return a boolean.

Change-Id: I3caf27782fb34e5e5474f40ef8d466bda61cd12c
Merge topic 'ply-reader-error' into master

486b71ee STLReader: Fix error signaling when reading files
37d058e5 STLReader: Close the file when an error occurs