fixes PHP notice
Allow the user to search for a range of years
i18n and graceful sorting for year values 'in press', 'submitted' and 'accepted'

The sorting mechanism relied solely on strcmp before, which yielded a more or less random result.
It is now possible to define an order as long as the strings in the bibtex file are given in their standard English form.
In output though, the strings are internationalised.
Made sorting of non-int year values easily configurable
Now also applies graceful ordering and i18n of non-string year-values to yearIndex()
Now displaying something sensible in result heading for Q_RANGE searches
Added css class and i18n to no “result” string
Escape German ß in addition to umlauts
Option FORCE_NAMELIST_SEPARATOR allows for commas between authors as well as between last and first name
Tidied up generation mechanism for [pdf], [doi] links etc.

Removed duplicate code that existed inside and outside of get*Link() functions.
Added option BIBTEXBROWSER_LINKS_IN_NEW_WINDOW. It is used instead of BIBTEXBROWSER_BIB_IN_NEW_WINDOW for external links (everything but [bibtex]).
Turns doi, url, gsid etc. into hyperlinks in bibtex entry display

Does not yet work in js progressive enhancement mode
added compare_bib_entry_by_name()
Splitted list layout by year; added BIBTEXBROWSER_HTMLHEADINGLEVEL
Added result count to every bibliography section in academic display, total count in normal display
Added a table of contents to search results in academic display
added copyright notice
Fixed a bug where '0 results' would be shown with the corresponding heading being invisible
updates documentation
adds an initial test suite
fixes a minor regression