Right to die with dignity: Does an adult have right to end his or her life?

Does an adult have a right to end his or her life? The answers to this question are often coloured by religious beliefs. The big problem is that no religion takes modern medical technology into account and, therefore, every religion is critically under-informed when it comes to providing answers to 21st century life and death situations.
 
Modern medicine introduces options that lie somewhere between death and life. It is entirely possible, actually common, for somebody to be in a coma for an indefinite period, with physical functions run by life-support machines. No religion deals coherently with the Schrodinger-esque situation