Remove local copies of stb headers, and use a submodule instead

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "third_party/stb"]
+	path = third_party/stb
+	url = https://github.com/nothings/stb

CMakeLists.txt

@@ -21,3 +21,5 @@ find_library(IMG2KTX_ISPC_TEXCOMP_LIB
   DOC "the ispc_texcomp library to link against"
 )
 target_link_libraries(img2ktx PRIVATE ${IMG2KTX_ISPC_TEXCOMP_LIB})
+
+add_subdirectory(third_party)

README.md

@@ -3,8 +3,7 @@ img2ktx
 
 img2ktx is a simple command-line utility.
 
-It currently runs on Windows, Linux and MacOS.  Use [CMake](https://cmake.org) to generate
-a project file for your platform.
+It currently runs on Windows, Linux and MacOS.
 
 It loads images with [stb_image](https://github.com/nothings/stb). Supported formats include
 JPEG, PNG, BMP, TGA, GIF, etc.
@@ -20,11 +19,24 @@ It writes the compressed images to a [KTX](https://www.khronos.org/opengles/sdk/
 If more than one image is provided with identical dimensions, the output KTX file can be either a
 2D texture array or a cubemap.
 
+Compile
+-------
+img2ktx uses submodules for its dependencies. After cloning the repository, be sure to fetch
+these dependencies:
+```
+$ git submodule update --init
+```
+
+Then use [CMake](https://cmake.org) 3.15+ to generate a project file for your platform.
+
+Binaries
+--------
 Download pre-built binaries from the [Releases](https://github.com/cdwfs/img2ktx/releases) page.
 
-That's it!
 
-It may eventually do the following things as well:
+TODO
+----
+img2ktx may eventually do the following things as well (but no promises):
 
 - Output [DDS](https://msdn.microsoft.com/en-us/library/windows/desktop/bb943991(v=vs.85).aspx) files,
   because inevitably somebody is going to ask for it.

img2ktx.cpp

@@ -2,14 +2,14 @@
 
 #pragma warning(push,3)
 #define STB_IMAGE_IMPLEMENTATION
-#include "stb_image.h"
+#include <stb_image.h>
 
 #pragma warning(disable:4702)  // unreachable code
 #define STB_IMAGE_RESIZE_IMPLEMENTATION
 #define STBI_MALLOC(sz) malloc(sz)
 #define STBI_REALLOC(p,newsz) realloc(p,newsz)
 #define STBI_FREE(p) free(p)
-#include "stb_image_resize.h"
+#include <stb_image_resize.h>
 #pragma warning(pop)
 
 #include <algorithm>