Small edits to novice R lesson on functions.
Updated section on defining an R function.
Indent with 2 spaces instead of 4. This is in agreement with Hadley and Google style guides.
Updated Composing Functions.
Added first call stack image.
Added stack frame images and explanations.
Replaced section on scoping and environments with short Tip that points to outside references.
Updated section on encapsulation.
Replaced exercises using paste and strsplit with easier exercises that simply slice vectors.
Updated challenge on drawing stack diagram with nested function calls.
Updated section on testing and documenting functions.
Updated challenge to write analyze function.
Removed section on function that does not return value because we use that function later in the lesson. We don't users accidentally using the incorrect function.
Removed reference to debugging section. Skipping because R does not have the same issue with integer division.
Updated section on Testing and Documenting to use read.csv and also to focus on vectors instead of matrices.
Added rescale challenges along with answers.
Updated section on Defining Defaults.
Added answer to challenge of rescale function with arguments.
Updated Objectives and Key points.
read.table -> read.csv in R lesson 02.