[OS] bt_main - Close UART at last possible opportunity.
[GIT] *.bak and .config.old added to .gitignore
[OS] Debug messages added in bt_fs.c
[OS] DIR configuration added to os/Kconfig
[OS] DIR dependency added to FS configuration in os/src/fs/Kconfig
[MMC] Block write supported added
[FS] Support of seek, EOF and openening files for writing added
[FS] FullFAT - Corrected a bug when FF_SHORTNAME_CASE is not enabled.
[FS] FullFAT - Handle mount errors from FullFAT gracefully.
[FS] FullFAT - Enabled FF_SHORTNAME_CASE in fullfat configuration.
[MM] SLAB - Fixed a bug in the slab allocator when it falls back to page allocation.
[DRIVERS] SDHCI - Removed sdcard debug messages.
[FS] Added BT_Rename and BT_Remove api, and implemented in FullFAT layer.