Removing invalid check for ACK in I2C receive function

Removing invalid check for ACK in I2C receive function

Fixing delay calculation for blinking LED based on Jerry's comment

Implement stopwatch

* Modify timer library to add capture functionality
* Add stopwatch control to main menu

Implement ring buffer

 * Integrate ring buffer with UART RX
 * UART RX interrupt enabled & ISR implemented
 * HW multiplier disabled in compiler flags
 * Delay added to main loop (for demonstration purposes only)

Implementing UART driver and menu

* Adding new files for UART driver
* Adding new files for menu
* Initialize UART in board_init
* Add menu to main application

Implementing timer library

* Create timer library API
* Implement Timer_A1 ISR
* Initialize timer module for SMCLK and clock divider 2
* Modify application to use timer library

Changes for new build system

 * New src directory
 * New include directory
 * New makefile added
 * Main code split into modules
 * README updated
 * .gitignore update

Lesson 6 changes

* Configured ACLK to VLOCLK
* Implement watchdog functionality
* Implement P1.3 interrupt

Refactored checksum calculation