Added qual format identifer; Added print FASTA/FASTQ functions; Smarter Makefiles;

1) Makefiles:
  - only recompile if a dependency has changed
  - added DEBUG option
2) Added seq_guess_fastq_format
3) Added seq_print_fasta(), seq_print_fastq(); used them in tools/seq_cat.c
4) Tidied up seq_stat.c; moved it to tools; compiles into bin/seqstat
5) Sketched wrote code needed to read a SAM/BAM through open_fh - at the moment
   opening a FILE stream with htslib is not possible, need to look into this