Fix help completion at the beginning of function body

[kapilmb]

Resolves #478

Comment help auto-completion does not work correctly for block comment ('<#') trigger characters at the beginning of function body - the auto-completed help does not contain the parameters. When the user types '<', it invalidates the following param block such that the parser does not recognize it as a param block, which results in the help not containing the parameters.

# the '<' before the param block leads the parser to not recognize the param block.
function foo {
  <    
  param($param1)
}