We should implement the code peek feature. For example, by pressing a hotkey, the declaration of the symbol under the cursor is shown in a source code viewer popup. By using this, users do not need to jump to other locations in the source code to quickly check the declaration. Tasks: - [x] code peek for included ASN1 file type - [x] fixing syntax highlighting of included ASN1 file type (now TTCN-3 syntax highlight is applied instead of ASN1) - [x] code peek in ASN1 file type