Add add_rows to add several rows at once

[hugovk]

When you have a list of rows, you can add them in one go with add_rows:

from prettytable import PrettyTable

x = PrettyTable()
x.field_names = ["City name", "Area", "Population", "Annual Rainfall"]
x.add_rows(
    [
        ["Adelaide", 1295, 1158259, 600.5],
        ["Brisbane", 5905, 1857594, 1146.4],
        ["Darwin", 112, 120900, 1714.7],
        ["Hobart", 1357, 205556, 619.5],
        ["Sydney", 2058, 4336374, 1214.8],
        ["Melbourne", 1566, 3806092, 646.9],
        ["Perth", 5386, 1554769, 869.4],
    ]
)

print(x)

+-----------+------+------------+-----------------+
| City name | Area | Population | Annual Rainfall |
+-----------+------+------------+-----------------+
|  Adelaide | 1295 |  1158259   |      600.5      |
|  Brisbane | 5905 |  1857594   |      1146.4     |
|   Darwin  | 112  |   120900   |      1714.7     |
|   Hobart  | 1357 |   205556   |      619.5      |
|   Sydney  | 2058 |  4336374   |      1214.8     |
| Melbourne | 1566 |  3806092   |      646.9      |
|   Perth   | 5386 |  1554769   |      869.4      |
+-----------+------+------------+-----------------+

[codecov]

Codecov Report

Merging #75 into master will increase coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #75      +/-   ##
==========================================
+ Coverage   87.22%   87.31%   +0.09%     
==========================================
  Files           3        3              
  Lines        1487     1498      +11     
==========================================
+ Hits         1297     1308      +11     
  Misses        190      190              

Flag	Coverage Δ
#GHA_Ubuntu	87.31% <100.00%> (+0.09%)	⬆️
#GHA_Windows	87.31% <100.00%> (+0.09%)	⬆️
#GHA_macOS	87.31% <100.00%> (+0.09%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/prettytable/prettytable.py	82.25% <100.00%> (+0.04%)	⬆️
tests/test_prettytable.py	100.00% <100.00%> (ø)

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