New "decode as ..." feature for BER-encoded files (WTAP_FILE_BER).

A BER-encoded file can be dissected as one of a number of registered syntaxes (registered using register_ber_syntax_dissector()). 
Syntaxes may also be associated with OIDs (or other strings) using register_ber_oid_syntax(). 

A default syntax with which to dissect a BER-encoded file is determined from its filename (extension). For example, ".cer" and ".crt" files will be dissected as "Certificate".


svn path=/trunk/; revision=20414