This action can be called by plugin to suggest user list of auto-completion strings. This may be needed by some abbreviation expansion plugins, similar to Zen Coding.
Suggestions list is Chr(13)-separated list of strings, each string is simply id or "|"-separated list: "id|type|(parameters)".
Parameters:
Return value: cSynError
if some parameters are not valid (e.g. strings list is empty), or cSynOK
otherwise.
Example for A2 parameter: if caret is in position 1:4 after word "wwww", and length parameter is 3, then last 3 "w" chars will be replaced with suggested string (which is chosen by user from popup window if it's enabled).