clang/gcc: enable a bunch more warnings (#91)

* clang/gcc: enable -pedantic warnings

* suppress a GCC-specific warning in stb_image

* And some clang-specific warnings

* -Wconversion (clang) -Wold-style-cast (clang+gcc)

and fix a few warnings that show up with these (and a few more with
-Wconversion on gcc, even though that's not enabled by default)

* bunch more warnings

* fixes

* remove merge error

src/tests/unittests/CommandAllocatorTests.cpp

@@ -203,7 +203,7 @@ TEST(CommandAllocator, LargeCommands) {
 
     const int kCommandCount = 5;
 
-    int count = 0;
+    uint32_t count = 0;
     for (int i = 0; i < kCommandCount; i++) {
         CommandBig* big = allocator.Allocate<CommandBig>(CommandType::Big);
         for (int j = 0; j < kBigBufferSize; j++) {
@@ -260,14 +260,15 @@ TEST(CommandAllocator, ManySmallCommands) {
     iterator.DataWasDestroyed();
 }
 
-//        ________
-//       /        \
-//       | POUIC! |
-//       \_ ______/
-//         v
-//    ()_()
-//    (O.o)
-//    (> <)o
+/*        ________
+ *       /        \
+ *       | POUIC! |
+ *       \_ ______/
+ *         v
+ *    ()_()
+ *    (O.o)
+ *    (> <)o
+ */
 
 // Test usage of iterator.Reset
 TEST(CommandAllocator, IteratorReset) {

src/tests/unittests/MathTests.cpp

@@ -64,7 +64,7 @@ TEST(Math, AlignPtr) {
 
         ASSERT_GE(aligned - unaligned, 0);
         ASSERT_LT(static_cast<size_t>(aligned - unaligned), kTestAlignment);
-        ASSERT_EQ(reinterpret_cast<intptr_t>(aligned) & (kTestAlignment -1), 0);
+        ASSERT_EQ(reinterpret_cast<uintptr_t>(aligned) & (kTestAlignment -1), 0);
     }
 }