add debug mode for transforms

Debug mode

It is now possible to visualize every transforms details, by simply adding the options -debug when calling go2pins, it will create a debug/ directory in the output directory with all transforms output. Every transforms go files is prefixed with its index.

For example, calling go2pins -debug test.go would produce:

00-transform-alive-1.go
01-transform-waitgroup-1.go
02-trransform-channel-1.go
...

Cleanup main.go

At the same time, main.go was too heavy and has been redesigned to be more comprehensible.

Options are now in tools/options.go, the program's entry is now in tools/entry.go and the compilation process has been set in tools/compile.go.