Implement search_regex from #847
implement fallbacks and defaults in _search_regex
print WARNINGs during test + minor fix to NBAIE
raise exceptions on warnings during tests - and solve a couple of them
use search_regex in new IEs
XHamster: Can't see the description anywhere in the UI
print "please report this issue on GitHub" on every ExtractorError
do not ask the user to report network errors
_html_search_regex with clean_html superpowers
test: extend the reach of info_dict checking

* print the info_dict in a format suitable to easy adding to tests.json during tests if un-tested fields are detected
* make it possible to put the crc32 in tests.json if the field is too long
* complete the "info_dict" fields in existing tests
* fixed the bugs catched doing this
switch long info_dict fields checking to md5
use _search_regex in GenericIE
Merge branch 'search_regex' - PR #872 - closes #847
add _search_regex to the new IEs