Documented new `proc:read()`; core/.proc.luadoc
Requires lspawn r18.
Added block comment support for reST and YAML; modules/textadept/editing.lua
Use `spawn()` for launching help; modules/textadept/keys.lua
Fixed bug in opening Manual from Help menu; modules/textadept/menu.lua
Fixed bug when double-clicking message buffer; modules/textadept/run.lua