Source Map line numbers are wrong with mocha and ts-node

[Dzeri96]

So as the title says, when I run this package with mocha like so:
why-is-node-running node_modules/.bin/_mocha --inspect -r ts-node/register 'src/**/*.test.ts'
or so:
mocha --inspect -r ts-node/register -r why-is-node-running/include 'src/**/*.test.ts'
the output points to the wrong line in the ts source files or even the wrong file completely.

[mafintosh]

PR welcome