Minimally functional version of show-docs for variant reporting
Put all printing into show-docs

Each component can add its own sections to the documentation
which are all printed in a standard place
Add overview doc section
Add doc to full reporter
Expose interface for type lookup to use in tests
Add required method
Test to compare docs output for variant reporting
Clean up how property lines are concatenated
max_name_length isn't used anywhere
Add property type to docs
Fix types
Simplify property doc printing, which removes trailing spaces
Rename variable for clarity
Use ceiling when estimating needed disk space.

(In my case, I was testing with a file <1KB in size and it estimated
needing 0 disk, which is clearly too small.)
Spelling: excute to execute.
Don't compare warning messages
owner on GMSchema is optional

When using the GENOME_TEST_FILLDB feature this object fails error
checking due to `owner` being `undef`.  To correct this the `owner`
should be labeled as optional.
remove cell_type from sync classes
remove cell_type attribute from sample classes
remove cell_type from views