If upgradable instances are found, bring a new dialog to inform user about it. This gives user a
chance to deselect "database instance" feature early, because experience shows nobody really looks at features and their in their description in "customize setup" dialog. This also tells user
that existing instances can be upgraded.
Allow MSI and NSIS side-by-side installation if installed NSIS package
differs in "major.minor" version numbers. Still disallow MSI and NSIS
if major.minor versions of both packages match.
Problem: user without privileges can have an half-complete
installation, if he manages to click on "Ignore" for all errors
in the installer.
As a result, he will miss ARP registry keys, and uninstall
will not be possible using "Add/Remove Programs" applet.
The general technique to generate MSI using CMake is taken from MySQL 5.5
Additional features not present in 5.5 installer :
-optionally creating a new database
(as Windows service), using new mysql_install_db.exe to do the job
- optional upgrade of existing services from old MySQL or Maria installation.
This work is actually done by the upgrade wizard that is launched at the
end of installation.
