[cvs-nhc98] Improve various comments, error messages, and formatting.

malcolm: Thu Aug 23 17:03:37 CEST 2001 Update of /usr/src/master/nhc/src/compiler98 In directory hinken:/tmp/cvs-serv20612 Modified Files: Main.hs Need.hs NeedLib.hs PreImport.hs PrettySyntax.hs Log Message: Improve various comments, error messages, and formatting. Merged from stable-1-06-branch.