HTML/Razor/Handlebars as extension

fixes #11309

Display language identifier in Language Mode drop down

* use electron 1.3.4

* ATOM_SHELL_INTERNAL_RUN_AS_NODE => ELECTRON_RUN_AS_NODE

* OSS input

* update electron.d.ts

* workaround for #8708

* bump oniguruma and chokidar with custom fsevents

* build with appveyor config from master

* oops, still use ELECTRON_RUN_AS_NODE

* use electron 1.3.5

* optional fsevents

* add cat.exe to workaround output issues

* use cat for tests

* remove some now obsolete ELECTRON_NO_ATTACH_CONSOLE

* also pipe output to cat for code.sh on windows

* unset ELECTRON_RUN_AS_NODE for appveyor

* fix tfs builds?

* fix build

* fix build?

* use cat only when running tests locally

Fixes #11990

Part of #10917

Fixes #11969

Add shellArgs. Fix #10917

Fixes #11972