Introduce an additional level of verbosity

[nddrylliog]

Levels:

• quiet (no option): really shut up
• -v: verbose, display some info about progress
• -vv: verboser, display some info about progress + full commands launched
• -vvv: veryVerbose, everything (info about resolver, etc., can make logs of several MB)

[nddrylliog]

Compilation log with rock -v now:

Parsing...
Resolving...
Generating C sources...
Compiling with 8 threads...
vpkg, 
Compiling 1 modules
[CC] vpkg
sdk, 
Compiling 55 modules
[CC] lang/Abstractions
[CC] lang/Buffer
[CC] lang/BufferIterator
[CC] lang/Character
[CC] lang/Exception
[CC] lang/Format
[CC] lang/IO
[CC] lang/Iterators
[CC] lang/Memory
[CC] lang/Numbers
[CC] lang/String
[CC] lang/System
[CC] lang/types
[CC] lang/VarArgs
[CC] structs/ArrayList
[CC] structs/List
[CC] math/Random
[CC] os/Time
[CC] native/win32/types
[CC] structs/HashMap
[CC] threading/Thread
[CC] threading/native/ThreadUnix
[CC] math
[CC] threading/native/ThreadWin32
[CC] native/win32/errors
[CC] threading/native/MutexUnix
[CC] threading/native/MutexWin32
[CC] threading/native/ThreadLocalUnix
[CC] threading/native/ThreadLocalWin32
[CC] structs/Stack
[CC] structs/LinkedList
[CC] os/Terminal
[CC] os/native/TerminalUnix
[CC] os/unistd
[CC] os/FileDescriptor
[CC] os/native/TerminalWin32
[CC] lang/Backtrace
[CC] os/Env
[CC] os/Dynlib
[CC] os/ShellUtils
[CC] io/File
[CC] io/FileReader
[CC] io/Reader
[CC] io/FileWriter
[CC] io/Writer
[CC] os/Pipe
[CC] os/native/PipeUnix
[CC] os/native/PipeWin32
[CC] io/BufferWriter
[CC] io/BufferReader
[CC] io/native/FileWin32
[CC] io/native/FileUnix
[CC] text/StringTokenizer
[CC] io/StringReader
[CC] lang/internals/mangling

Linking...
[LD] vpkg
[ OK ]

Cleaner, yes?