Improve error messages

[4brunu]

Hello, this PR fixes #20.

It show's more explicit errors and add a verbose flag that prints all shell commands and the respective responses.

Here is an example of how the error are showed now:

/usr/bin/xcodebuild clean build -dry-run -project XcodeProject.xcodeproj -target XcodeProjectTarget -UseModernBuildSystem=0 -sdk iphonesimulator -destination platform=iOS Simulator,name=iPhone X,OS=latest
Terminated with the status 65.
User defaults from command line:
    UseModernBuildSystem = 0

Build settings from command line:
    SDKROOT = iphonesimulator12.0

Prepare build
note: Using legacy build system

=== CLEAN TARGET XcodeProjectTarget OF PROJECT XcodeProjectTarget WITH THE DEFAULT CONFIGURATION (Debug) ===

Check dependencies
[BEROR]No architectures to compile for (ONLY_ACTIVE_ARCH=YES, active arch=i386, VALID_ARCHS=arm64 armv7s).

Create product structure
/bin/mkdir -p /Users/User/Developer/XcodeProject/build/Debug-iphonesimulator/XcodeProjectTarget.app

Clean.Remove clean build/XcodeProjectTarget.build/Debug-iphonesimulator/XcodeProjectTarget.build
    builtin-rm -rf /Users/User/Developer/XcodeProject/build/XcodeProjectTarget.build/Debug-iphonesimulator/XcodeProjectTarget.build

Clean.Remove clean build/Debug-iphonesimulator/XcodeProjectTarget.app
    builtin-rm -rf /Users/User/Developer/XcodeProject/build/Debug-iphonesimulator/XcodeProjectTarget.app

** CLEAN SUCCEEDED **

Prepare build
note: Using legacy build system

=== BUILD TARGET XcodeProjectTarget OF PROJECT XcodeProjectTarget WITH THE DEFAULT CONFIGURATION (Debug) ===

Check dependencies
No architectures to compile for (ONLY_ACTIVE_ARCH=YES, active arch=i386, VALID_ARCHS=arm64 armv7s).


** BUILD FAILED **


The following build commands failed:
	Check dependencies
(1 failure)

[lvsti]

I'm afraid waitUntilExit cannot be used here since it depends on a runloop being installed on the current thread

[4brunu]

Done

[lvsti]

coud you please reformat this like:

guard
    xxx,
    yyy
else {
    zzz
}

?

[4brunu]

Done. The Xcode auto-formatting put it like this:

guard
    xxx,
    yyy
    else {
        zzz
}

It is ok? Or should I change it?

[lvsti]

👍