Draw Harness, ViewerTest - improve vinit command for resetting viewer state option

Tests usually perform viewer initialization in the following way:

pload VISUALIZATION
vclear
#vclose ALL
vinit View1 -w 512 -h 512
vaxo

It should be noted that some actions look redundant (vaxo, which is default viewer orientation) and has awkward order (vclear is done before vinit).
This is done to allow re-evaluating the same test twice or different tests within the same Draw Harness instance (e.g. avoiding DRAWEXE restart).

The procedure is, however, incomplete and clumsy.
It is desired extending vinit command with new arguments to:
- Reset View position to defaults (avoid explicit vaxo call afterwards).
- Clear View content (avoid explicit vclear call beforehand).
- Apply provided View dimensions or reset them to default 409x409 if View already was created (avoid vclose ALL just to ensure View having requested dimensions).
- Optionally reset View parameters like background, rendering params to default.
- Optionally close all other Views (avoid vclose ALL call beforehand), e.g. -single.