Rename cc::options::exec to cc::options::parse

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>
Catch cc::options thrown exception in main

Do not catch the std::exception thrown from `cc::options::parse' in
`cc::application::exec', catch it in the `main' function instead.

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>
Move --support implementation to print_support

This allows us to initialize libquvi after parsing the input URLs. The
rationale behind this is that it is pointless to initialize libquvi
unless we have input.

`--support' on the other hand requires this immediately, therefore
dedicate the `print_support' function for this purpose.

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>
Throw "no input URL" from cc::input

The exception (std::runtime_error) will be caught in the `main' function.

Signed-off-by: Toni Gundogdu <legatvs@gmail.com>