1. memory optimize;
2. add irom version libm.a: libmirom.a;
3. more apis are supported in libcirom.a, such as sscanf, sprintf, etc;
4. add c++ support in Makefile;
5. put functions to iRAM default, don't need ICACHE_FLASH_ATTR anymore;
6. remove -O2 in Makefile;
7. fix some fatal exception bugs;
8. update smartconfig to version 2.4.7;
9. update some open source files and header files;
10.use os_printf can save memory;
11.add new apis: os_random and os_get_random;
12.bug fix in lwip/net80211/wpa modules;
13.other minor changes;
1). update smartconfig to v2.2;
2). add some new APIs;
3). fix bugs in net80211 and wpa;
2. update smart_config demo;
3. fix a bug in app demo;
***internal version 0f73a14a***
