Numerous warnings when compiling CMOR

[mauzey1]

When CMOR is built using make, the C compiler will output many warnings. A lot of them are related to snprintf, which is due to the destination string potentially being not long enough to store the entire string being generated.

Src/cmor_CV.c: In function 'cmor_CV_checkExperiment':
Src/cmor_CV.c:1473:58: warning: '%s' directive output may be truncated writing up to 1023 bytes into a region of size 1002 [-Wformat-truncation=]
                                  "Your input attribute \"%s\" with value \n! \"%s\" "
                                                          ^~

Some are due to comparisons between different data types.

Src/cmor.c: In function 'cmor_pop_traceback':
Src/cmor.c:434:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i = 0; i < strlen(cmor_traceback_info); i++) {
                   ^

Some are due to function declarations that should be prototypes in the header files. Functions that don't have parameters should be declared with (void) instead of ().

In file included from ./include/cmor.h:578:0,
                 from Src/cmor_variables.c:4:
./include/cmor_func_def.h:15:1: warning: function declaration isn't a prototype [-Wstrict-prototypes]
 extern void cmor_set_terminate_signal_to_sigint();
 ^~~~~~

Although we could suppress these warning messages, it would be better to fix these issues in the code.