Added bunch of macros to make configuration changes less error prone.
Added ability to detect previous install directory entries in the registry.
Searches for entry in HKLM and HKCU sections.
Tidied-up some of the functions.
HKLM... depending on whether the user is restricted (or doing a current
user-only install) or is installing for all users.
Refactored some of the Booleans.
Windows 9x/ME installs shortcuts for the current user (desktop, start menu)
but defaults to install in the 'Program Files' directory like everything
else.
user installation types. Works for a restricted user. Bit weird on Windows
9x - will fix. Needs matching installers for stamps, prevention of execution
of tuxpaint-config by restricted users, registry entry.
