Add print_alignment function

[thequilo]

The print_alignment function prints a seglst-style alignment as produced by meeteval.wer.wer.time_constrained.align(..., style='seglst') in a human-readable format. This makes discussing alignments, such as in #113, easier.

import meeteval
alignment = meeteval.wer.wer.time_constrained.align(
   [
         {"words": "hi", "start_time": 0.93, "end_time": 2.03},
         {"words": "good how are you", "start_time": 3.15, "end_time": 5.36},
         {"words": "i'm leigh adams", "start_time": 7.24, "end_time": 8.36},
         {"words": "pretty good now and you", "start_time": 9.44, "end_time": 12.27},
         {"words": "yeah", "start_time": 15.49, "end_time": 16.95},
     ],
     [
         {"words": "hi", "start_time": 0.93, "end_time": 2.03},
         {"words": "are you", "start_time": 3.15, "end_time": 5.36},
         {"words": "leigh adams", "start_time": 7.24, "end_time": 8.36},
         {"words": "good now and", "start_time": 9.44, "end_time": 12.27},
         {"words": "yep", "start_time": 15.49, "end_time": 16.95},
     ], style='seglst'
)
meeteval.wer.wer.time_constrained.print_alignment(alignment)

 0.93  2.03     hi - hi     1.48  1.48
 3.15  3.83   good + are    3.70  3.70
 3.83  4.34    how + *
 4.34  4.85    are + you    4.81  4.81
 4.85  5.36    you + *
 7.24  7.50    i'm + *
 7.50  7.93  leigh - leigh  7.52  7.52
 7.93  8.36  adams - adams  8.08  8.08
 9.44 10.33 pretty + good  10.01 10.01
10.33 10.93   good + *
10.93 11.38    now - now   11.00 11.00
11.38 11.82    and + *
11.82 12.27    you + and   11.85 11.85
15.49 16.95   yeah + yep   16.22 16.22

[boeddeker]

How about adding a sentence to the readme?
A pointer to this PR may also help. Alternatively, the example could be shown in the readme. If it is too long, it could be put in a details html tag.