Filter board column on more than one label

[darenwelsh]

Some potential issues after initially thinking this through:

• Do we assume for a column, if the user lists 2 or more labels, that their intent is to list actions with either (OR) label? Or do we assume they only want actions that have both (AND) labels? Or are we supposed to accommodate both options?
• This seems like it'll make the optional "None of these labels" column query very difficult to specify

[darenwelsh]

For the optional "None of these labels" column, a different approach would be to

1. query for actions that meet the criteria of each column
2. make an array of these actions represented in defined columns
3. make another array of actions using the filters for the whole board
4. make a new array based on the diff of the first two arrays
5. use that diff array to define which actions to show in the optional "None of these labels" column

[darenwelsh]

Decision: For now, only accommodate AND conditions for multiple labels defining a column. For example, if someone lists Label:In work and Label:Urgent to define a column, only show actions that have both labels.