newlib uses significantly more stack space when printing to an
unbuffered stream. To reduce the amount of stack space required to
use the console, don’t disable buffering. linenoise should support
unbuffered stdout instead.
This change adds a check for compatibility between the nvs version
found on nvs flash and the one assumed by running code during nvs
initialization. Any mismatch is reported to the user using new error
code ESP_ERR_NVS_NEW_VERSION_FOUND.
