Clean up summary file generation

This change straightens out, consolidates, and cleans up summary.html
generation.

Testing done:

Ran VDDReporter.
Rearrange methods in VDDReporter

This change rearranges the methods in the VDDReporter class so that related
methods are close to one another.  No code was otherwise modified.

Testing done:

Compiled and ran VDDReporter
Clean up issues.html generation

This change cleans up and optimizes the generation of issues.html in
VDDReporter.

Testing done:

Ran VDDReporter, looked at output.
Rename VddLogIssues to Issues part 1

This change renames VddLogIssues to Issues.
Rename VddLogIssues to Issues part 2

This change renames VddLogIssues to Issues.

Testing done:

Compiled and ran VDDReporter
Clean up the Issues class

This change cleans up, simplifies, optimizes, and documents the Issues class.

Testing done:

Compiled and ran.