change memory usage to bit fields

[Sanaloht]

char arrays for parsed cronexpr changed to uint8_t* bit fields
added tests for memory allocation

[staticlibs]

Hi, the PR looks good, thanks! The only unclear thing is, why gmtime_s changed to gmtime on windows?

Besides that, can you please make it pass "compile and test" commands from here at least for some of the compilers? I really like to keep it "warning-free", currently cannot test the updated version with my app because of warnings.

[staticlibs]

Forgot another bit, could you please rename TEST macro to CRON_TEST_MALLOC or something like this?

[Sanaloht]

Macroname is fixed and use of the define extended.
The gmtime_s issues are partially due to c89 standard but mostly due to mingw32.
Defines now change if mingw is used. Can you test it now?

[staticlibs]

@Sanaloht Thanks for the update! Smoke tests are passing for me. Going to look deeper and merge it in a day or two.

[staticlibs]

Merged and fixed and changed some minor things. Overall bitfields are very nice to have. Thanks again for PR!

[ThomTe]

You're welcome and thanks to Niondir for helping!