Use fixed-width font for task parameters (in scheduler, manual task execution...)

When writing task parameters, Clover currently uses the default font which is a proportional font. This makes it harder to work with parameters or code in many places since things do not align properly.
Please change the parameter edit boxes so that they use non-proportional (fixed-width) font. This means changing the font in (might not be all the places):

• Scheduling: graph parameters, various task parameters (like email body...)
• Event listeners: all kinds of event parameters (graphs, events, groovy code...)
• Sandboxes: file editor (file content is already using proper font)