Added maxLines config option to MultilineInput  (#4477)
Added maxLines config option to MultilineInput  (#4477)

* Added maxLines config option

* Made maxLines_ protected

* Added parentheses

* fontsize fix

* Enabled scrollbars at overflow of y axis

* Added ellipsis handling for overflow Y

* Deleted unused variable

* Added an explanation comment
rachel-fenichel/blockly,google/blockly,google/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,google/blockly,google/blockly,mark-friedman/blockly,google/blockly,mark-friedman/blockly,google/blockly,mark-friedman/blockly,mark-friedman/blockly,mark-friedman/blockly,rachel-fenichel/blockly,mark-friedman/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,google/blockly