Fixes for file type identification.

- Backed out eTag changes.  The real world is more complicated
   than just using eTags to identify the same file.
 - A bit of code simplication in the http base scripts.
 - Test updates (more existing small problems were identified!).
 -

testing/btest/Baseline/scripts.base.frameworks.file-analysis.http.partial-content/b.out

@@ -21,7 +21,5 @@ FILE_GAP
 FILE_STATE_REMOVE
 file #1, 206024, 816896
 [orig_h=192.168.72.14, orig_p=3257/tcp, resp_h=65.54.95.14, resp_p=80/tcp]
-FILE_BOF_BUFFER
-\x1b\xb8=\xb1\xff^PU^P\xce\xc3^
 total bytes: 1022920
 source: HTTP