Added text on ! wildcard and combining and nesting wildcards.
Started writing about escaping wildcard characters.
Moved explanation of escaping special characters into a box.
Code creating the file file[AB].txt.
More on ls file[AB].txt.
What happens if we create fileA.txt.
Example of escaping wildcard characters.
Changed starter text for Escaping Special Characters box.
Moved wildcard stuff in Pipelines section to Wildcard section.  Needs to be merged into that text.
Moved all material on wildcards from Pipes and Filters into Wildcards section, including from objectives and summary, but kept that text in italics so we can merge it into surrounding text.
Small modification to text at beginning of Pipes and Filters.
Change of wording to text at beginning of Pipes and Filters.
Starting revising text at the beginning of Wildcards section.
Continued writing about file* example.
Moved stuff about asterisk into a box.
Finished text box on asterisk wildcard.
Put four types of wildcards into a bulleted list.
Edited bullet point about square brackets.
Edited bullet point about exclamation mark.
Edited bullet point about curly braces.