Add CMake build system plus other goodies

[ljacobson64]

This main content of this PR is adding the CMake build system. Other additions with this PR include:

• Adding a script that runs all of the sample problems
• Adding a script that diffs the sample problem output against assumed-to-be-correct output
• Updating the readme to reflect the CMake build system and the new sample file running procedure
• Updating the install guide (there is some duplicated information between this file and the readme; perhaps information should only be in one place or the other?)
• Adding documentation showing how to build the documentation
• Changing the source branch when building the documentation from master to main
• Fixing a common typo where "opened" is misspelled as "openned"

[ljacobson64]

@gonuke Did you mean to make more posts here? Not sure what you're asking

[gonuke]

Thanks @ljacobson64