Added ecoli correct examle and kmer-agnostic with error

1. Added ecoli example for read correction
2. Added script to download data for results
3. ctx_contigs.c, ctx_correct.c, ctx_coverage.c, ctx_exp_abc.c: Fixed memory
   calculation
4. src/tools/assemble_contigs.c fixed double counting of repeat ends
5. Started adding kmer agnostic tests for seqn with error