WIP: Summary PDF rework

[mtlam]

From our discussions, this PR is intended to revamp the summary PDFs. Not all of the information will transfer to a new PDF, and some is moved to either a revamped par_checker or CI. This uses a spiritual successor to report.py, but instead of logging information as it streams in, the report must be actively built.

Included files:

• markdownreport.py - includes the MarkdownSection and MarkdownReport classes. These act more generically and are used to store and generate the appropriate information.
• summarizer.py - include the Summarizer class used to generate the report. These include timing-specific calls and glues everything together.

To-dos:

• Finish transferring items from old pdf_writer()
• Remove or deprecate old pdf_writer()
• Unit testing
  • markdownreport
  • summarizer