Add new method to obtain the time and date from the RTC without requiring a DateTime object.

[Mark-Wills]

Description

The PR adds a new method to the MCP7940_Class object which populates a DateTime_t struct with the time and date as read from the RTC. The intention is to provide a method to to obtain the time and date without requiring a DateTime object.

Prototype:
bool getTimeDate(DateTime_t&);

Example usage (arduino code shown):

char dtStr[35];
MCP7940_Class RTC

void setup()
{
  RTC.begin(); // assumes the RTC has already been set
}

void loop()
{
  DateTime_t dt;
  RTC.getTimeDate(dt);
  snprintf(dtStr, sizeof(dtStr) - 1, "Time: %02u:%02u:%02u, Date: %04u/%02u/%02u\n",
           dt.hour, dt.minute, dt.second, dt.year, dt.month, dt.day);
  Serial.print(dtStr);
  delay(1000);
}

Fixes # (issue)
N/A

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Doxtgen update required. I have included comments in the code which are hopefully compatible with Doxygen.

How Has This Been Tested?

Tested in ESP32 environment on Arduino platform as per the example shown above. Requires minimal testing the the new method does no memory allocation/de-allocation.

Checklist:

• The changes made link back to an existing issue number
• I have performed a self-review of my own code
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• The code adheres to the Google Style Guide
• The code follows the existing program documentation style using doxygen
• I have made corresponding changes to the documentation / Wiki Page(s)
• My changes generate no new warnings
• The automated TRAVIS-CI run has a status of "passed"
• I have checked potential areas where regression errors could occur and have found no issues
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes