Modify throttle status bar mod to be able to display multiple values

[chros73]

Modify status bar mod (#4, #37) to be able to display multiple throttle.up and throttle.down as well, also change name of config directive.

Currently the beginning of status bar looks like this:
[Throttle 500/1500 KB] [Rate: 441.6/981.3 KB]

Include the max limit of the throttles, the main upload rate and the upload rate of the throttles (in this order); and main download rate and the download rate of the selected throttles.

Possible cases look like these:

[Throttle 200 / 500 KB] [Rate 107.4 / 298.6 KB]
[Throttle 200(114) / 500 KB] [Rate 107.0(1.0|105.9) / 307.6 KB]
[Throttle 200 / 500(250) KB] [Rate 124.7 / 298.2(298.2|0.0) KB]
[Throttle 200(114) / 500(250) KB] [Rate 115.9(1.7|114.2) / 333.9(333.9|0.0) KB]

[Throttle 3500(75|25) / 8000 KB] [Rate 1745.5(1635.1|85.0|25.4) /   7.3 KB]

• make the displayable throttle names configurable via config file: ui.status.throttle.up.set and ui.status.throttle.down.set
• original code is refactored
• throttle.up and throttle.down values can be specified simultanously (as in the last example)
• name of throttles must be specified without surrounding quotes (the setting no longer a string but a list)
  • ui.status.throttle.up.set = slowup , tardyup
  • ui.status.throttle.down.set = slowup
• limitation is that every group (there are 4 possible groups) can contain the following number of characters (it leaves space for at least 5 throttles to be displayed):
  • limit: 40 chars
  • rate: 50 chars
• don't display this extra info of a given throttle in the following cases:
  • there isn't any throttle name as the config variables suggest or the given name is "NULL"
  • the throttle is not throttled (=0)
  • the global upload/download is not throttled (=0) (the throttle won't be taken into account in this case)

Refers to: #4 , #37