test(test_suite): added support for PRINTF_DISABLE_SUPPORT_EXPONENTIAL

fix(printf): remove float comparison

Add more float test cases

fix(printf): fixed support of NaN

(hot) fixes #37

fix(printf): fctprintf() must not append null terminator

Fixes #39, references #19

chore(printf): cleanup secure strlen() function, added test cases

Merge remote-tracking branch 'origin/master'

chore(catch): update to catch2 2.4.2

chore(printf): small improvments

fix(printf): fix hash precision

Fixes #31

chore(readme): update readme