Fix #252

Fixes more than what is discussed in pull request #252:
- If a von-prefix occurs, add all the first letters to the shortened name, e.g.
	"Jeroen van de Graaf", Crypto 2010 => C:vdGraaf10
- Some names have been updated, but the labels were still outdated, e.g.
	[EC:Burmester90a] => [EC:BurDes90]
- Delicate care is taken into account that some keys were colliding so a "dis"-disambiguation is added, e.g.
	[EPRINT:UnrDom12] & [EPRINT:Unruh12] => [EPRINT:Unruh12a] & [EPRINT:Unruh12b]

Author: ludopulles