fix "Cannot read property includeInto of undefined" error

[mfripp]

This fixes an error in pool.js that causes an error message "Cannot read property includeInto of undefined" (and no table) to appear when opening csv/tsv files with the Table Editor.

It appears that vm.runInContext() does not return a copy of the class when called with an ES6 class declaration, although it may have returned a copy of the class when called with a coffescript class declaration in the past. This pull request refers to the class at the end of the source code, which causes vm.runInContext() to return the class instead of undefined. This prevents the error noted above.

This fixes issues #100 and #101.

[corymalcolmtaylor]

I tested it and it worked for me on win 10 with latest atom. Thanks!

[jnmandal]

Using branch in my atom and I can't open any CSV files at all once the package is installed. No error messages, it just shows the empty pane. Atom 1.28.2 on macOS 10.13.6

edit: Adding that when double clicking a csv file (default to opening in atom) it creates a separate instance of Atom.app which won't close and has to be killed forcefully

[ajgreyling]

Confirm it is fixing the issue on Mac OS 10.14.1 (18B75) Atom 1.34.0 x64

[PhilippeComte]

Feb 21 2019 Not working on Mac OS 10.13.6 High Sierra Atom 1.34.0 x64

[amitbattase]

Worked for me.

[Jackson-H-Chen]

Getting the same error :(