Testing ts1.4

[Phaiax]

• resolved null vs undefined (see issue xyz)
• multiple root files
• if no rootfile in commandline, rootfiles will be fetched from tsconfig.json
• fixed bug with partial updates

[clausreinke]

done, with a few changes:

• null vs existence
• accept multiple root files
• fix tsconfig.json logic, and accept tsconfig "files"

I haven't added the tsconfig.json - it will be ignored anyway when there are files on the command line (according to the pull request that introduced the feature - I've updated tss behaviour to match).

I had marked the update calculations "Check" because TS kept changing back and forth between 0- and 1-indexed line/col calculations. But your suggested change would drop a character (can be observed in the script.out2 output for partial-update.script).

Thanks for your suggestions.