CMakeLists.txt: cmake min required 3.13 -> 3.5 using CMAKE_REQUIRED_LIBRARIES; add ZINT_COVERAGE option

bmp/emf/ps.c: allow for foreground colour in ULTRA
bmp/gif/pcx.c: allow for BARCODE_STDOUT (fflush/fclose)
emf.c: hexagon rotation field not used; dont't use float index in font loop; Windows stdout binary mode
png.c: remove unused 8-bit; simplify libpng error handling and fclose outfile on error
ps.c: fix buffer overflow on colour_to_pscolor() CMYK
tif.c: fix BLACKISZERO indexes
CODE39: simplify check digit setting
reedsol.c: rs_uint_init_gf() log/alog tables must be zeroed
ZBarcode_Encode: debug: fix access out-of-bounds on non-NUL-terminated source if length < 10
manual.txt/zint.h: document NUL-terminated strings
tests: cover further cases for output (bmp/emf/etc), eci/gb18030/gb2312/sjis, reedsol, AZTEC, CODE39

backend/tests/test_sjis.c

@@ -139,6 +139,7 @@ static void test_sjis_utf8(int index) {
         /*  2*/ { "β", -1, 0, 1, { 0x83C0 }, "" },
         /*  3*/ { "¥", -1, 0, 1, { 0x5C }, "" },
         /*  4*/ { "aβcЖ¥･ｿ‾\\＼点茗テ", -1, 0, 13, { 'a', 0x83C0, 'c', 0x8447, 0x5C, 0xA5, 0xBF, 0x7E, 0x815F, 0x815F, 0x935F, 0xE4AA, 0x8365 }, "" },
+        /*  5*/ { "\200", -1, ZINT_ERROR_INVALID_DATA, -1, {0}, "Invalid UTF-8" },
     };
     int data_size = ARRAY_SIZE(data);
     int i, length, ret;