Update cm.window.title API.
Update cm.window.title API.

Refactor. Prohibit non-string values(null, undefined too) in title text.

fauvel/CM,mariansollmann/CM,mariansollmann/CM,fauvel/CM,alexispeter/CM,cargomedia/CM,alexispeter/CM,tomaszdurka/CM,fvovan/CM,mariansollmann/CM,tomaszdurka/CM,zazabe/cm,vogdb/cm,fauvel/CM,zazabe/cm,njam/CM,njam/CM,fvovan/CM,fvovan/CM,zazabe/cm,vogdb/cm,alexispeter/CM,cargomedia/CM,njam/CM,vogdb/cm,tomaszdurka/CM,vogdb/cm,fauvel/CM,vogdb/cm,cargomedia/CM,alexispeter/CM,tomaszdurka/CM,njam/CM,njam/CM,zazabe/cm,tomaszdurka/CM,fvovan/CM,mariansollmann/CM,cargomedia/CM,fauvel/CM