It is similar to a string comparison (for string sorting) but unlike
the usual strncmp() or
strncasecmp() functions, when digits are encountered in a string, they are converted to a number and
this is the number value which is taken in account for comparison.
This is especially useful to sort component references or value.
For instance:
when the 2 strings U12 and U2 are compared by ASCII value:
In usual comparison (from ASCII value), U120 is sorted before U20
In StrNumCmp:
120 is read as a integer value
20 is read as a integer value
and comparisons are between U<120> and U<20> where <120> and <20> are integers, not chars.
and U120 is sorted after U20
