add two more ignores related to eclipse projects.

THis is necessary for newer Boost (1.71) which puts the exported targets
in Boost_LIBRARIES. If we export that verbatim it causes link issues on
projects using the config scripts from Make

This reverts commit e7294d81.

This does not exist on xenial yet

find_package is for use inside the *Config.cmake files

To add public dependencies to the generated config, use e.g.

list(APPEND ${PROJECT_NAME}_PUBLIC_DEPENDENCIES "Boost COMPONENTS system thread chrono")

- Make doxygen pick up markdown.
- introduced: set_default_build_to_release.cmake

set_default_build_type_to_release.cmake -> set_default_build_to_release.cmake

'*.md' files put into the projects doc directory will be picked as part of
the documentation. '*.md' files in other locations of the source tree will
be ignored.

enclose CMAKE_BUILD_TYPE in quotes; this transforms it into an wmpty
string and the string command wont complain that its missing an argument
when CMAKE_BUILD_TYPE is not set.

Cmake treats CMAKE_BUILD_TYPE string as case insensitve. Make the check
for enabling coverage reflect this to make usage less restrictive.