[FIX] don't reevaluate the report for generate_html

generate_html evaluates the report first. This report may already have
been evaluated and now wait evaluated in the attributes of the
object. Thus, we now check whether the report is analyzed already and if
so don't evaluate it again. Since a report without sections is not
allowed then number of sections being bigger than 0 is a good sign for
an already evaluated report.
Also, reevaluation only worked because multiple entry point functions
(parse into sections) threw existing information away before
starting. This code is no longer needed if we don't reevaluate.
[FIX] removed debug code

Even if debug code is commented out it makes the actual code harder
to read. If you need a print for debugging, put it in but do not commit
it.
[TEST] for single lazy plans without explicit section start

Check whether a single lazy plan works correctly even without explicit
section start headers.
[FEAT] Support single lazy plans without explicit section start

When we have lazy plans (i.e. plans after the of lines) we can no longer
use the plan as section start. Therefore, we used to require explicit
section start headers in that case.
For only one test plan this is in fact not necessary. Instead when we
only have one plan the we necessarily have only one section. The single
lazy plan is so common that it makes sense to handle it special. With
this change the user no longer needs to add special Tapper header to
prevent parse errors to TAP he gets out of standard TAP tools.

cr https://cr.amazon.com/r/1536480/
added Amazon Tapper Team as author to dist.ini
Merge tag 'opensource-reviewed'