Fix D2 compilation.
Update from new author.
Use PathCombine for if DestName starts with a slash (PathDrivePartLengthEx doesn't always leave of the trailing slash).
See https://github.com/jrsoftware/issrc/commit/3ee150d87904306baeed2468af94b4ddd802adf3#commitcomment-2418559, reverted: Use PathCombine for if DestName starts with a slash (PathDrivePartLengthEx doesn't always leave of the trailing slash). (reverse-merged from commit 3ee150d87904306baeed2468af94b4ddd802adf3)
Check for :

See https://github.com/jrsoftware/issrc/issues/26#issuecomment-12136160

#26
Chop off any {tmp}\ prefix. #26
Add length check and use PathLowercase instead of UpperCase. #26
Doc ExtractTemporaryFiles. Closes #26.
Tweak SaveStringsTo(UTF8)File 'seealso's.
If the Flags parameter of a [Files] entry includes isreadme and the entry also has a BeforeInstall or AfterInstall parameter, the BeforeInstall or AfterInstall functions will now only be called when the file is installed and no longer a second time when the file is viewed file after the installation has completed.

Closes #36.
Typo fix. Thanks @sschuberth. #36.