Default to file extension for source format

[mcint]

When a file is passed as an argument, we should use the file extension as a input type hint unless an explicit --input parameter is passed.

Current behavior

Yaml parse without argument

$ lq . .rustup/settings.toml
"default_toolchain = \"stable-x86_64-unknown-linux-gnu\" profile = \"default\" version = \"12\"\n[overrides]"

Unwieldy long string, yaml parse of a single string representation of the whole document including newlines.

Expected json output

$ lq --input=toml . .rustup/settings.toml
{
  "default_toolchain": "stable-x86_64-unknown-linux-gnu",
  "overrides": {},
  "profile": "default",
  "version": "12"
}

Desired behavior

For at least these formats of filename, lq should just do the right thing.

• $ lq . doc.json
• $ lq . doc.yaml / $ lq . doc.yml
• $ lq . doc.toml

[clux]

Ah, that is a nice suggestion. Thank you. Would simplify usage a bit as well. I can have a quick go at this.