imageviewer: Initial support for JPEG progressive images. Add lib sources

Added unmodified files from RAINBOW library by Attila Tarpai
Full sources:
https://github.com/Halicery/vc_rainbow

Change-Id: I356486b6a332aa3f610ddcae57f8a2044653b051

apps/plugins/imageviewer/jpegp/GETC.h

@@ -0,0 +1,56 @@
+/* 
+  "GETC" Interface for byte input (i.e. started as a wrapper for getc())
+
+	For image- and video decoders I needed a transparent mechanism for 
+	opening and reading the input data: 
+
+		- either from streams (eg. coded video)
+		- or preloaded into memory (eg. small GIF/PNG images)
+
+	RAINBOW is only dependent on the GETC Interface for byte input. 
+
+	File stream input is used during development and testing (FILEGETC.C). 
+	In the OS image Rainbow can be linked with MEMGETC.C for memory input. 
+	No other changes necessary in RAINBOW. 
+
+*   Copyright (c) 2017 A. Tarpai 
+*   
+*   Permission is hereby granted, free of charge, to any person obtaining a copy
+*   of this software and associated documentation files (the "Software"), to deal
+*   in the Software without restriction, including without limitation the rights
+*   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+*   copies of the Software, and to permit persons to whom the Software is
+*   furnished to do so, subject to the following conditions:
+*   
+*   The above copyright notice and this permission notice shall be included in all
+*   copies or substantial portions of the Software.
+*   
+*   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+*   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+*   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+*   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+*   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+*   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+*   SOFTWARE.
+*/
+
+
+// For decoders
+
+extern int GETC();
+
+// Multibyte helpers
+extern int GETWbi();	// read word (16-bit) big-endian
+extern int GETWli();	// little-endian
+extern int GETDbi();	// read double word (32-bit) big-endian
+extern int GETDli();	// little-endian
+
+// positioning
+extern void SEEK(int);	// move relative to current
+extern void POS(int);	// move absolute position (TIFF)
+extern int TELL();		// read actual position 
+
+
+// For RAINBOW clients to implement outside of Rainbow Library
+extern void *OPEN(char*);
+extern void CLOSE();