Checks stream size when reading in BER format
adding const qualifiers for security.[c|h] helps understand inputs and
outputs
check stream sizes when reading ClientInfoPDU
checks stream sizes when reading redirection packets
checks stream sizes when reading GCC packets
checks stream size when processing channel data
checks BER decoding result and stream size when processing NLA packets
checks stream size when reading rail strings
checks stream size in rail client channel
Merge pull request #887 from hardening/hardening1

Adding security checks