NewliquidCrystal example HelloWorld_i2c just flickers
I was able to make the example run as intended, by using a different constructor call:

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);


I am not able to tell you, what these parameters and values mean. However, the documentation for this constructor is shown below (source). 

/*!
    @method     
    @abstract   Class constructor. 
    @discussion Initializes class variables and defines the I2C address of the
    LCD. The constructor does not initialize the LCD.

    @param      lcd_Addr[in] I2C address of the IO expansion module. For I2CLCDextraIO,
    the address can be configured using the on board jumpers.
    @param      En[in] LCD En (Enable) pin connected to the IO extender module
    @param      Rw[in] LCD Rw (Read/write) pin connected to the IO extender module
    @param      Rs[in] LCD Rs (Reset) pin connected to the IO extender module
    @param      d0[in] LCD data 0 pin map on IO extender module
    @param      d1[in] LCD data 1 pin map on IO extender module
    @param      d2[in] LCD data 2 pin map on IO extender module
    @param      d3[in] LCD data 3 pin map on IO extender module
    */
   LiquidCrystal_I2C( uint8_t lcd_Addr, uint8_t En, uint8_t Rw, uint8_t Rs, 
                     uint8_t d0, uint8_t d1, uint8_t d2, uint8_t d3 )
;