Improve reminder & alarm code

[stesie]

Hi again,

this patch

• refactors the words to timestamp conversion code of the reminder & alarm setting code. The same piece of code was present three times in very similar versions
• uses alarmd instead of at to do the notification (which wasn't listed as a dependency anyways)
• make sure the actual message is passed to espeak
• alarm is set even if time and message are in the first piece of input
• refactors resetting of next_func to before calling it. This way not every next_func needs to reset next_func individually

cheers,
stesie