Added reset process to zero function

to replace the current workaround of using allow negative & allow positive together to zero a process chain.
Additional processlist buttons for /,x,-,+ feed

Recently added /,x,-,+ feed functions and the reset functions currently show as uninformative grey tags on the process list chain on the inputs page, added 5 new functions to processlist 'keys' and added a 4th "type" combining the colour and label style of "+ input" type with the "link to vis" functionality of the "log to feed" type.
changed reset tag test

shortened "RESET" to "=0" to reduce size of button and match existing allow pos and allow neg tags
Merge pull request #181 from pb66/processlist

Processlist buttons for inputs page