Ignore build artifacts in textbook directory.
Fixed typo: specifically to [series]
Fixed an error found by Donald Parker
Crediting Donald Parker for his contribution
Not quite ready to release power series
Merge pull request #28 from clark-archer/textbook-housekeeping

Ignore build artifacts in textbook directory.
Merge pull request #29 from clark-archer/4.1-absolute-convergence

Fixed typo: specifically to [series]
Created exercise for identifying a power series from among non-power-series
Created exercise for finding the interval of convergence where the series converges at just one endpoint
A couple more problems for homework 5
A quiz problem to differentiate a power series term by term with some custom distractors
Homework question asking students to approximate erf
Coursera students finding errors
Final draft of textbook content
Pagerdef just emits its parameter