Big addColumn, addField and Seed refactor (PART2)

[romaninsh]

In this part I've implemented Table::addColumn() as per requirements in #188.

demo/table.php works well now, but other pages still fail. Some additional documentation needed here, but other UI elements will be resolved in PART3.

Approve / Merge #179 before this.

[codecov]

Codecov Report

Merging #223 into epic/atk-core-refactor will decrease coverage by 7.59%.
The diff coverage is 58.53%.

@@                     Coverage Diff                     @@
##             epic/atk-core-refactor     #223     +/-   ##
===========================================================
- Coverage                     39.02%   31.43%   -7.6%     
  Complexity                     1053     1053             
===========================================================
  Files                            58       58             
  Lines                          2483     2488      +5     
===========================================================
- Hits                            969      782    -187     
- Misses                         1514     1706    +192

Impacted Files	Coverage Δ	Complexity Δ
src/Table.php	26.66% <58.53%> (-40.71%)	77 <21> (ø)
src/TableColumn/Template.php	0% <0%> (-87.5%)	5% <0%> (ø)
src/TableColumn/Money.php	0% <0%> (-87.5%)	7% <0%> (ø)
src/TableColumn/Delete.php	0% <0%> (-83.34%)	5% <0%> (ø)
src/CallbackLater.php	0% <0%> (-60%)	4% <0%> (ø)
src/TableColumn/Link.php	34.28% <0%> (-57.15%)	20% <0%> (ø)
src/TableColumn/Generic.php	6.52% <0%> (-56.53%)	21% <0%> (ø)
src/jsExpression.php	60.75% <0%> (-16.46%)	36% <0%> (ø)
src/Callback.php	10.71% <0%> (-10.72%)	8% <0%> (ø)
... and 4 more

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[DarkSide666]

looks good

[DarkSide666]

don't we have more types ?

[romaninsh]

did we?