Load TTF files without installing.

Quoted: The PrivateFontCollection class allows applications to install a private version of an existing font without the need to replace the system version of the font. For example, GDI+ can create a private version of the Arial font in addition to the Arial font that the system uses. PrivateFontCollection can also be used to install fonts that do not exist in the operating system. This is a temporary font install that does not affect the system-installed collection. To see the installed collection, use the InstalledFontCollection class.