[FIX] std::fstream Adaption: added functions open and close

git-svn-id: http://svn.seqan.de/seqan/trunk@14579 e6417c60-b987-48fd-844e-b20f0fcc1017
[FIX] FileStream: fixed isReadable/isWritable, implemented function streamError

git-svn-id: http://svn.seqan.de/seqan/trunk@14580 e6417c60-b987-48fd-844e-b20f0fcc1017