Broken on big-endian architectures

The following tests fail in big-endian architectures:

The following tests FAILED:
	  1 - File transversal (Failed)
	  2 - Search for GCode blocks (Failed)
	  3 - Convert from binary to ascii (Failed)
	  4 - Convert from ascii to binary (Failed)

Downstream bug report in Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1062014

Some debugging reveals that this error happens due to mismatched endianness when reading data files.

diff --git a/src/LibBGCode/core/core.cpp b/src/LibBGCode/core/core.cpp
@@ -126,8 +127,10 @@ EResult FileHeader::read(FILE& file, const uint32_t* const max_version)
 {
     if (!read_from_file(file, &magic, sizeof(magic)))
         return EResult::ReadError;
+    printf("data=0x%08x MAGIC=0x%08x\n", magic, MAGICi32);
     if (magic != MAGICi32)
         return EResult::InvalidMagicNumber;

->

File:/build/libbgcode/tests/data/mini_cube_b.bgcode
data=0x47434445 MAGIC=0x45444347

It's likely that there are many more similar problems lurking in the source code.
If this issue can't be fixed, the package should probably be disabled on big endian architectures.

Sample build logs:

• https://buildd.debian.org/status/fetch.php?pkg=libbgcode&arch=s390x&ver=0.0%7Egit20231219.7aaf717-1%2Bb1&stamp=1704613965&raw=0
• https://buildd.debian.org/status/fetch.php?pkg=libbgcode&arch=ppc64&ver=0.0%7Egit20231219.7aaf717-1%2Bb1&stamp=1704984706&raw=0

Start with the failing File transversal, Search for GCode blocks, and binary/ascii conversion tests, then inspect data-file reads in src/LibBGCode/core/core.cpp, including FileHeader::read. Reproduce the failures on a big-endian architecture using the linked Debian build logs as context. Done means the listed tests pass on big-endian systems without disabling the package.