there is no need to clone() here,  it creates a memory leak as it's not attached the to DOM and therefore isn't removed by remove()

Trigger an event when columns are toggled on or off

The current templating approach is really inefficient, as it recursively loops thru every 
passed available variable for substituion and applies a regex for each one. 

It's much faster to initially parse the template and then only process those strings which are 
actually present in the template.

This revised implementation both caches the parsed templates and then only processes the string which are present.

The performance improvement is quite drastic, especially with large tables. A large table was previously taking 15s to render 
in Chrome, now takes less than 1s with this approach

rather than needing to recursively process every string, move the templated string for infos into the template definitions

added buttons to append 10, 100 and 1000 rows with logging of rendering time (on screen and to console)

don't set the replacement value to null when a property doesn't exist

added back in the old method and evaluate the template string using both approaches,
log out to console any different results found

refactored functions out from string and array protoypes
included appendRow changes from #285 (50% faster in Chrome, 10% Edge,
15% FF)

This reverts commit cef18bc.

remove prototypes from string and array
merge in appendRow #285  improves Chrome 50%, FF 15%, Edge 10%

no longer needed since appendRows