avoid conflicts with other taxonomy-based tools and keep script names consistent (also create taxonomy-directory during installation if not already existing)

[jvollme]

updateTaxonomy.sh and updateAccessions.sh would be most useful in the PATH. However their more generic name can be a problem if other taxonomy-based tools are installed and use the same naming scheme. To fix that, the KRONA naming scheme of the perl-scripts (with "kt" prefixes) is applied to these scripts via softlinking during installation: updateTaxonomy.sh --> ktupdateTaxonomy updateAccessions.sh --> ktupdateAccessions Both scripts are softlinked to the [prefix]/bin folder.

All instances mentioning the use of updateTaxonomy.sh or updateAccessions.sh in KronaTools.pm and install.pl have been corrected accordingly.