Make the TypeScriptFilter use relative paths, rather than a temp file

The TypeScript definition import mechanism (which uses relative paths) does not work correctly when using the relative path to a given TypeScript library.

e.g. ///< reference path="../../typings/jquery.d.ts" / >

Due to the way that the TypeScriptFilter was copying the .ts file to a temp directory in order for the compiler to generate javascript, these relative filepaths were broken

In this pull request I have removed the temp file creation; loading the .ts file directly allows the definition files to be resolved correctly by the filesystem.