Use editable fields for Row and Column range rather than sliders

[ieivanov]

We usually know the exact range of data we'd like to look at. Using the sliders that's hard / impossible to dial in exactly. I suggest replacing the sliders with editable text fields, e.g. Row range: <A1> - <H12> where both <A1> and <H12> are editable. These field can be automatically populated to span the range of wells in the data after the Load dataset button is clicked or a valid path is entered in the field next to it. After the user changes these fields to limit the range we should run a validation that the start/end wells are present in the dataset.