schemas/public_.sql: taxonlabel: added index on taxonomicname to facilitate retrieving rows from tnrs_input_name

inputs/.TNRS/schema.sql: added taxon_name_is_safe()

inputs/.TNRS/schema.sql: added unsafe_taxon_names()

fix: lib/tnrs.py: max_names: lowered to 50 because the dev TNRS server is now always crashing with an Internal Server Error when scrubbing 500 names at a time (https://github.com/iPlantCollaborativeOpenSource/TNRS/issues/7)

web/.htaccess: auto-detect dotpath in query string: also auto-prepend & for query strings appended to a username-based prefix, so that these don't need to have & manually prepended to make them appendable

web/.htaccess: auto-detect dotpath in query string: also auto-detect dotpath for query strings appended to a username-based prefix, so that these don't need to have . prepended to make them appendable

web/username_prefix.php: no prefix: use $_SERVER["SCRIPT_URL"] instead of rtrimming $_SERVER["REQUEST_URI"]

web/username_prefix.php: has prefix: use same expr whether or not it has a query string, because the with-query-string expr works for both cases

web/username_prefix.php: use if statements instead of `? :` for clarity

web/username_prefix.php: use $subpath instead of $_SERVER["PHP_AUTH_USER"] for clarity