(Reuters) - Caterpillar Inc on Friday forecast full-year earnings below analysts' expectations as it struggles with sluggish global industrial activity.The world's biggest construction and mining equipment maker said it expects 2020 profit of $8.50 per share to $10 per share, compared with the average analyst estimate of $10.63 per share."We expect continued global economic uncertainty to pressure sales to users in 2020 and cause dealers to further reduce inventories," Chief Executive Officer..