EmPy template syntax support for VSCode

Adds syntax highlighting to EmPy files in VSCode.

All templates should end with .em. A second extension can be used to select the grammar of the non-templated part, e.g. .cpp.em. Currently the following subgrammars are being supported:

• Batchfile
• C
• C++
• CMake
• Dockerfile
• Groovy
• HTML
• PowerShell
• Python
• Shell Script
• XML

Contributions are greatly appreciated. Please fork this repository and open a pull request to make grammar tweaks, add support for other subgrammars etc.