Investigate code coverage

[martinmoene]

• OpenCppCoverage
• Travis?

From project root folder, generate coverage report from given test program:

@echo off & setlocal

if [%1] == [] goto :Help

for %%x in (%~f0) do (
    cd build\test\Debug
    opencppcoverage --no_aggregate_by_file --sources %%~dpx -- %~nx1
)
endlocal & goto :EOF

:Help
echo Usage: %0 [test]

Progress:

• lest
• gsl-lite
• any-lite
• byte-lite
• expected-lite
• X - invoke-lite
• observer-ptr-lite
• X - optional-fun-lite
• optional-lite
• ring-span-lite
• X - scope-guard-lite (no code yet)
• span-lite
• status-value-lite
• string-view-lite
• value-ptr-lite
• variant-lite