Hide mouse cursor at startup

The mouse cursor is visible at startup, would be better to hide it.

Been looking around for a fix : this issue is specific to windows10, and no fix is available yet.

[ThomDevs]

Is it already implemented for other OSes ?
Can the option to display/hide the cursor (specifying it does not work for W10) be implemented in ZSpin?

To be (mostly?) solved in pull request #64. Cursor will only be shown in --debug mode.