Create new mame database: default db save location wrong

[Wanderer]

When selecting a mame.exe as "source datafile", the database name and location are proposed by RC. The default save location for the database is the same as the location of mame.exe. It probably should be saved under RC datas folder.

[Eric Bole-Feysot]

I added new default folders into settings

[Eric Bole-Feysot]

Removing version: 4.0.0b11 (automated comment)