GMNS v0.93

[ianberg-volpe]

Updates in this PR include responses to several issues, as well as feedback from the Zephyr Badgers.

Changes to the specification since v0.92 include:

• config file includes specification of units (closes #53) and coordinate system information
• more consistency with datatypes across specification files (e.g., when integer vs. numeric are used)

Changes to the supporting examples/tools include:

• fixes to Arlington example (closes #52) and inclusion of a "with-errors" version of Arlington to demonstrate validation tools.
• use of the example Lima network to demonstrate the Graph_Validation notebook
• minor documentation updates/clarifications

Voting on this pull request will open after the PMG meeting on June 29.

[xzhou99]