better thread management

[coderatul]

problems i encountered :

• pressing ctrl+c, did'nt terminated the script instead terminal had to be killed
• setting thread = 1, in option2, gave 403 error due to single thread

fixes

• better thread management for keyboard interuption

now ctrl+c stops the script

• added a new user agent for apparently reduced request failure
• user input for no. of threads, is +1 by deafult to avoid 403 error with single thread