parametric tslot library

make tslot of any width.
10x10
20x20
25x25
30x30
40x40
...
Version 120616.01:
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Edited Scad file for new OpenScad syntax (version 2012.05)

Version 120215.01:
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Corrected some bugs, added more objects to demo.


Version 120208.02:
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Simplified library, now you pass the model as a parameter.
Added more tslot models.

Version 120208.01:
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Added two slots for Wx2W
So now you can print
25x50
30x60
...