libragephoto 0.3.0 release

- update README.md
- update documentation
- ragephoto-gtkviewer: fix error uint8_t -> int32_t, NULL -> nullptr
- ragephoto-qtviewer: fix error uint8_t -> int32_t
- RagePhotoA: fix documentation, fix error()
- RagePhotoC: add brief

src/RagePhotoA.h

@@ -142,7 +142,7 @@ public:
         return ragephoto_loadfile(instance, filename);
     }
     /** Returns the last error occurred. */
-    uint8_t error() const {
+    int32_t error() const {
         return ragephoto_error(instance);
     }
     /** Returns the Photo Format (GTA V or RDR 2). */
@@ -171,19 +171,19 @@ public:
     const char* jpegData() const {
         return ragephoto_getphotojpeg(instance);
     }
-    /**< Returns the Photo JPEG sign. */
+    /** Returns the Photo JPEG sign. */
     static uint64_t jpegSign(uint32_t photoFormat, RagePhotoData *rp_data) {
         return ragephotodata_getphotosignf(rp_data, photoFormat);
     }
-    /**< Returns the Photo JPEG sign. */
+    /** Returns the Photo JPEG sign. */
     static uint64_t jpegSign(RagePhotoData *rp_data) {
         return ragephotodata_getphotosign(rp_data);
     }
-    /**< Returns the Photo JPEG sign. */
+    /** Returns the Photo JPEG sign. */
     uint64_t jpegSign(uint32_t photoFormat) const {
         return ragephoto_getphotosignf(instance, photoFormat);
     }
-    /**< Returns the Photo JPEG sign. */
+    /** Returns the Photo JPEG sign. */
     uint64_t jpegSign() const {
         return ragephoto_getphotosign(instance);
     }

src/RagePhotoC.h

@@ -31,7 +31,10 @@
 #ifdef __cplusplus
 extern "C" {
 #endif // __cplusplus
-/** \file RagePhotoC.h */
+
+/** C API for RagePhoto.
+* \file RagePhotoC.h
+*/
 
 /** RagePhoto C++ class typedef for C API. */
 typedef void* ragephoto_t;