Wrong addition solved in add_faux_rows by adding parseInt
Also added parseInt to the add_faux_cols method
Also added parseInt to the add_faux_cols method
Fix a bug in add_faux_cell

This line checks that the row doesn't already exist in the gridmap
array; if it does then it doesn't need to be pushed to the faux_grid
array.

Otherwise, this function introduced a bug when I was dynamically adding
widgets that had a row height > 1 as the first widget added. Any
subsequent widget added would end up being at row 2 (rather than row 3,
as the first widget already occupied the first 2 rows).
Merge remote-tracking branch 'rept/addition_problem_add_faux_rows' into 4box-perf-bug
4 or more box performance issue fixed. Thanks: @rept pull 426  @CodeAnimal pull 440