WithPropertyHeader: extract data by header text instead of column name

[imil]

A feature that was convenient to me, and might be useful for others:
Instead of searching for the property by column name, search by the header text.
Example:

| A | B
1| Product | Price
2| Tea | 0.9
3| Coffee | 1.5

Instead of writing
.WithProperty(p=>p.Price, "B")
it will be possible to write
.WithHeaderRow(1) //Optional: 1 by default
.WithPropertyHeader(p => p.Price, "Price")

Then, if another column gets inserted after A, moving Price to column C, no code modification will be needed.