gdbstub (not esp-gdbstub) inappropriately named

[riban-bw]

There is a third-party provided module called, "esp-gdbstub" which implements and interface with gdb debugger. There is also a module called, "gdb" which seems to catch exceptions and print some debug info to serial but does not implement a gdb interface. Naming this "gdb" and describing it within source code as, "A stub to make the ESP8266 debuggable by GDB over the serial port." is misleading and confusing. May I suggest this module be renamed and the description changed to be more appropriate?
Maybe this module should be called, "exception_handler" or similar. I note there is also code, "crash_handler" which may be appropriate to consolidate with this.

[slaff]

"gdb" which seems to catch exceptions and print some debug info to serial but does not implement a gdb interface.

stack_dumper is probably a better name. But I am open to suggestions. Stack dumper should be activated only in non-RELEASE mode.

crash_handler is something that is allowing user-based code to be executed after an exception was raised and do some minimal operations like save it to flash memory or just increase a number. the latter could be used in RELEASE and non-RELEASE mode.

[slaff]

Fixed with the merge of PR #1655.