Dwindle: single column/row limits (extend "single_window_*" parameters idea)

[Vladimir-csp]

Similar to single_window_aspect_ratio, but affecting a single row or column:

• single_column_aspect_ratio
• single_column_max_width
• single_row_aspect_ratio
• single_row_max_height

With corresponding *_tolerance options, I guess.

single_window_max_width, single_window_max_height also seem like a potentially useful addition.

I currently use this construct to roughly do max width to a single window, but there is no way to target a column this way:

workspace = r[1-10] w[tv1] f[-1], gapsout:0 $HGAP 0 $HGAP                                                                                                                         
workspace = r[1-10] f[1], gapsout:0 0 0 0

($HGAP is set dynamically via kanshi).