[DOC] Manual: small fixes to BamIO tutorial
[FIX] Build System: removed a debug message from FindSeqAn.cmake
[DOC] BamIO: documented contigLengths()
[API,DOC,TEST] BamIO: introduced getContigName() and getContigLength() to get reference sequence name and length from BamAlignmentRecord and BamFile
[DOC] Manual: explained getContigName() and getContigLength() in the BamIO tutorial