Updated create_field to set step to "any" if option is not specified.

number.php

function create_field( $field )
{
  $o = array( 'id', 'class', 'min', 'max', 'step', 'name', 'value' );
	$e = '<input type="number"';
	
	foreach( $o as $k )
	{
		$val = $field[ $k ];
		if ( $k == 'step' && empty($val) ) $val = 'any';
		$e .= ' ' . $k . '="' . esc_attr( $val ) . '"';	
	}
	
	$e .= ' />';
	
	echo $e;
	
}