share/simple_xls.py 0.0.7: update with new methods and some performance optimisations.

Adds various new methods to insert and append columns and rows, and improve internal
book-keeping in order to give significant performance gain over previous version.
RNA-seq/bowtie_mapping_stats.py 1.1.4: update how output spreadsheet is generated.
RNA-seq/bowtie_mapping_stats.py: 1.1.5, now correctly handles paired-end Bowtie2 output.