Automatic stack location selection (SYS or HEAP), enable per library AR-chive in arduino build system

cores/esp8266/cont.h

@@ -49,11 +49,7 @@ typedef struct cont_ {
         unsigned* struct_start;
 } cont_t;
 
-/* Not static, used in core_esp8266_postmortem.c.
- * Placed into noinit section because we assign value to this variable
- * before .bss is zero-filled, and need to preserve the value.
- */
-extern cont_t* g_pcont __attribute__((section(".noinit")));
+extern cont_t* g_pcont;
 
 // Initialize the cont_t structure before calling cont_run
 void cont_init(cont_t*);

cores/esp8266/core_esp8266_main.cpp

@@ -48,7 +48,7 @@ extern void (*__init_array_end)(void);
 /* Not static, used in Esp.cpp */
 struct rst_info resetInfo;
 
-/* Not static, used in core_esp8266_postmortem.c.
+/* Not static, used in core_esp8266_postmortem.c and other places.
  * Placed into noinit section because we assign value to this variable
  * before .bss is zero-filled, and need to preserve the value.
  */

doc/faq/readme.rst

@@ -55,16 +55,19 @@ How can I get some extra KBs in flash ?
 About WPS
 ~~~~~~~~~
 
-In release 2.4.2 only, WPS is disabled by default.  To enable WPS, use this
-boards generator option:
+From release 2.4.2 and ahead, not using WPS will give an exra ~4.5KB in
+heap.
+
+In release 2.4.2 only, WPS is disabled by default and the board generator is
+required to enable it:
 
 ``./tools/boards.txt.py --allowWPS --boardsgen``
 
 `Read more <a05-board-generator.rst>`__.
 
-From release 2.4.2 and ahead, using WPS will reduce available heap space to
-user by around 4.5KB.  In other words, from release 2.4.2 without using WPS,
-an extra ~4.5KB is available in user's heap space.
+This manual selection is not needed starting from 2.5.0 (and in git
+version).  WPS is always available, and not using it will give an extra
+~4.5KB compared to releases until 2.4.1 included.
 
 This Arduino library doesn't work on ESP. How do I make it work?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~