fixed memory leak in log_add_to_list()

replaced localtime() to thread save function localtime_r()

Feature 2302

fixed strfuncs_test warnings

Feature 2295

master->feature-2295

fixed warning

added dap_strlen(). String may be nullable.

[+] dap_log_level_get()
[*] Renamed log_level_set() -> dap_log_level_set()

Fixes for proper dapvpn-client building under Windows

added dap_log_set_max_item() for seting max items in log list

renamed log_get_item() -> dap_log_get_item()

added save logs in list

[+] digits convert
[+] min and max macros

[*] Replaced strtok() to strtok_r() for MT safe

[*] ifndef/define changed to pragma once
[*] dap_strdupv() changed its argument:   char ** -> const char **