[Lazarus] CHM help package

[Werner Pamler]

I cloned your repo on my HD, and went through it step by step while 
always trying to build lhelp, I could remove everything from the folder 
chm except for these units: chmfifimain, chmreader, chmsitemap, chmtypes 
(and chmobjinstance.inc). I think it is possible to extract the 
essential changes from these units to get at least the new reading 
functionality. I can try this - but: before beginning I'd like to get 
positive feedback from fpc devs that this will be merged (I have some 
old patches hanging around there, and it is not always motivating to 
submit fpc patches).

As for the unit lcid_conv: This fits into Lazarus' LazUtils, and should 
go there independently of how this story ends here. I have commit rights 
to Lazarus and can put it there. Any objections?