Add support for reading from stdin? about bat HOT 2 CLOSED

# read from keyboard
bat

# read c++ from keyboard
bat -l c++

# read from stdin/file
bat -l md < README.md

# read from stdin/pipe
bat README.md | bat -l md

# output main.rs, then Cargo.toml, then printer.rs
bat src/main.rs - src/printer.rs < Cargo.toml

# write something to a file quickly
bat > file

# see issue '#4':
curl -s https://raw.githubusercontent.com/sharkdp/bat/master/README.md | bat -l md