Block scoping causing problems in older browsers

[RocketMan]

The changes introduced by #140 adversely affect browsers which do not yet support javascript block scoping that was introduced in ECMAScript2015.

For example, an older version of Chrome gives this error when using FindIt!
Uncaught SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode

[RocketMan]

commit b4361f8 replaces block scoping with higher-order functions to implement closure; the latter should be supported even in older browsers

Patch landed hotfix-2-8-0, prod; closing