Fixes qax-os#195: Make GetRows return value avoid empty cell

* qax-os#195: proposed resolution to the issue

* Make GetRows return value avoid empty cell

* Update test file to fix broken testing.

Comments style changed.

Simplify testing code, add test case for outline functions and update…

… the godoc.

GitHub repo URL changed.

Bugfix: deep copy issue with function `CopySheet()`, relate PR qax-os…

…#108.