added version 1.51 changelog

changelog.txt

@@ -1,3 +1,41 @@
+SGDK 1.51 (April 2020)
+----------------------
+
+COMPILER
+* APPACK
+ - fixed build for 32 and 64 bit linux (thanks doragasu)
+* LZ4W
+ - minor fix  
+* RESCOMP
+ - added new sprite optimization options to SPRITE resource (see rescomp.txt for details)
+ - minor tweak on binary export order (can save some bytes with LZ4W compression)
+ - fixed resource duplication bug
+* XGMTOOL
+ - fixed VGM loop
+
+LIBRARY
+* fixed corrupted library binaries which were displaying a blank screen on some MD models
+* MEMORY
+ - fixed a minor in memory packing operation
+ - added MEM_pack() here and there to avoid memory fragmentation
+* VDP
+ - fixed getAdjustedVCounterInternal(..) which could return value > 255 in some rare situation
+ - moved VDP DMA busy checking on reset (better to do it before accessing VDP)
+ - VDP_setPlaneSize(..):
+   - added constraint on plane size
+   - fixed maps start address calculation (when VRAM setup is asked)
+ - minor change in VDP_drawImageEx(..) to do setTileMap(..) operation using CPU (DMA is actually slower here)   
+* added SYS_showFrameLoad() / SYS_hideFrameLoad() methods to monitor CPU frame load.
+* always load font using CPU in reset process (safer)
+* fixed String unit build when ENABLE_NEWLIB set (thanks doragasu)
+* improved documentation in Joy unit (thanks Chilly Willy) and VDP (regarding DMA QUEUE usage specifically)
+
+SAMPLE
+* reduced memory usage on sample which use Bitmap mode by reducing DMA allocated memory
+* SPRITE
+ - added SYS_showFrameLoad() showcase
+
+
 SGDK 1.5 (April 2020)
 ---------------------