Docs improvements

Fix a typo
Add link to I2C unlock procedure.

Both thanks to @rtek1000 .

Access to last one byte of RTCs RAM : PR #37

Access to last one byte of RTCs RAM : PR #37

Minor release, no change on functionality. BIG thanks to @BenUniqcode

Add error check to refresh function

Now this function returns bool value, false on errors: PR #36

Thanks to @BenUniqcode

v.6.8.0 - 12/24h, improvements and bugfixes ( #27 ): PR #35 - Thanks to @pk17r

Here is some more functionality and bug corrections:

• I2C communication blocking bug in enableBattery() and disableBattery() mostly hitting on ESP32 and sometimes on Atmega328p. enableBattery() not always working bug. Closes #27
• addition of 12 hour / 24 hour clock mode select functionality
• flag to know if clock is in 12 hour / 24 hour mode and also AM-PM if in 12 hour mode
• added 12-24 hour mode select comment on example; a print statement that'll print AM-PM if in 12 hour mode
• model check before accessing SRAM or alarms, refresh() needs to be called before calling lostPower()
• bug correction on eosc flag, introduced in my last commit
• bug correction on not noting alarmClearFlag while clearing alarm flags, introduced in my last commit
• tabs replace spaces, introduced in my last commit
• tested all functionalities on Atmega328p and ESP32.

That's it! Thank you!

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This release (and previous one) is 100% by @pk17r . Thank you!

EOSC flag, docs and lot of improvements

• reduced class size by 3 bytes
• added function descriptions to header file so they show up on Arduino IDE while hovering over functions
• added an EOSC flag to check if oscillator will run on VBAT or not and that time will not increment on power loss
• correction in Day of Weeks, Sunday is 1
• under alarmTriggered function description explicitly mentioning that A1F and A2F will be triggered whether or not A1IE and A2IE are enabled or disabled
• added above information on readme as well
• minor corrections

Thanks to @pk17r - PR #34

Binary masks were wrongly set as hexadecimal numbers

v6.6.1 - Fix binary masks, thanks to @lbovet , #PR31

Enhancenments, 32Kout and alarmTriggered

• AlarmTriggered functionality, @derbic7 idea
• 32K Output control functions. As DS1307 lacks this pin, it's mapped to SqWG output.
• Refresh functionality improved for DS3231 and DS3232; now it refreshes all data with less operations. Now any other function doesn't refresh data from RTC.

AlarmClear fixes

AlarmClear fixes, thanks to @derbic7 , fixes #25

Aging register control

Added agingGet and agingSet functions in order to control aging value on DS323X RTCs.

You can see its usage here: https://github.com/Naguissa/uRTCLib/blob/master/examples/uRTCLib_example_full/uRTCLib_example_full.ino#L64

Suggested by @eleksir on #23

enable/disable battery and ATTiny support

Added enableBattery support (DS3231 and DS3232) - thanks to @mrfaptastic
Added disable battery complementary function
Added ATTiny support