Convert option weechat.look.hotlist_sort to a list of hdata fields

[flashcode]

Feature description

Based on this comment: #1235 (comment)

The new format is a comma-separated list of hdata fields, using hdata "hotlist" (var) and "buffer" (buffer.var).

The old value (enum) is automatically converted to a string, and the format of weechat.conf is bumped:

• group_time_asc → -priority,time,time_usec
• group_time_desc → -priority,-time,-time_usec
• group_number_asc → -priority,buffer.number
• group_number_desc → -priority,-buffer.number
• number_asc → buffer.number
• number_desc → -buffer.number

Each field can start with this char (they can be combined):

• -: reverse order
• ~: case insensitive string comparison

For example to sort on a buffer local variable called my_priority: buffer.local_variables.my_priority.

Note: be careful, for buffer local variables, comparison is made between strings, so for example "10" < "5".