Description fixes

[sean-fitzpatrick]

Quality control fixes to images in Section 1.1. More to come for other sections, so keep open for now.

[sean-fitzpatrick]

@Alex-Jordan I've done a first pass through the descriptions in Chapter 1.

I'll work on getting the HTML rebuilt ASAP. If these look all right to you, I can merge, and look over later chapters when I have more time.

[Alex-Jordan]

Thanks Sean! I haven't reviewed your descriptions, but I'm sure they are good and I wouldn't quibble.

Removing firstcurvestyle seems like it will have unwanted side effects. Just off the top of my head, any function where the graph needs to be drawn with two components, and the components are drawn using these open, openclosed, etc. styles. Two components means you don't want to use addplot+ for them. But if you are using open, etc, you've lost the stuff like firstcolor that is set in firstcurvestyle.

[sean-fitzpatrick]

I ran a global search on each of those styles. In almost all cases where they are used with addplot and not addplot+, firstcurvestyle was specified (e.g. as addplot [firstcurvestyle, openclosed]). In the few cases where this wasn't the case, I added it in.