Added a default argument to the string object.  There's no reason you cannot specify a default string.
Updated string unit tests.  Added create check.
Merge branch 'master' into cstrings

Conflicts:
	src/tests/unit/test_pstring.c
pact_string_new defined and implemented.
pact_string_free defined and implemented.
pact_string_get_cstr defined and implemented.
pact_string_get_length defined and implemented.
pact_string_copy_cstr defined and implemented.
pact_string_substr defined and implemented.
pact_string_compare defined and implemented.
pact_string_compare_cstr defined and implemented.
pact_string_copy defined and implemented.
pact_string_find defined and implemented.
pact_string_find_after defined and implemented.
pact_string_find has been changed to an inline function that calls pact_string_find_after with an offset of 0 and returns the result.
pact_string_find_after_cstr defined and implemented.
All pact_string_find* functions are now inline functions that call to pact_string_find_after_cstr.
pact_string_chop_front defined and implemented.
pact_string_chop_back defined and implemented.
Data in pact_String changed to constants.
pact_string_concat defined and implemented.
pact_string_split and pact_string_split_cstr defined and implemented.
Removed old string code.