This patch allows certain commands (`debug`, `test`, and `trace`) to
take an argument specifying a package name. This allows a user to
specify a package other than that of the current package in the working
directory.

If a package name is not specified, the behavior remains the same, as in
Delve will look in the current working directory for a `main` package to
compile.

Fixes #423

Implements #368

1. A running goroutine is by definition not parked waiting for a
chan recv
2. The FDE end address is intended to be exclusive, the code
interpreted as inclusive and sometimes ended up setting a breakpoint
on a function other than the current one.

Past the maximum recursion depth maps shouldn't be loaded at all,
adding map children and not loading them breaks assumptions in
the prettyprinter.

Fixes #406

I was hoping this will fix the issue below.
But there is more code that break new cgo rules.

Fixes #409 (partial)

Fixes #398.

Fixes #370.

Fixes #397

Mainly just cleans up the code in cmd/dlv/main.go

Fixes #392

Fixes #384

The tracepoint should be set on the function's first line, not the
function's entry point to avoid function prologue weirdness.

Fixes #389

Fixes #355

Fixes #378

Insure that the digits function always returns at least 1.

Fixes #354 (partial)

If uninitialized memory is read loadArrayValues could try to call
cacheMemory with a negative size, which could cause a 'makeslice:
len out of range' panic.

Fixes #354 (partial)

Fixes #370.

Fixes #361

I need a proof-reader...

This patch modifies the `step` command to step to the next source line,
stepping into any function encountered along the way.

Fixes #360

Typedefs that resolve to slices are not recorded in DWARF as typedefs
but instead as structs in a way that there is no way to know they
are really slices using debug/dwarf.
Using golang.org/x/debug/dwarf instead this problem is solved and
as a bonus some types are printed with a nicer names: (struct string
→ string, struct []int → []int, etc)

 Fixes #356 and #293

This change addresses a Windows-specifc issue with the 'test' command. On
Windows, 'go test' generate executables with a '.exe' filename extention,
but the current implementation attaches to a filename without the
extention.

Instead of doing a bunch of manual DWARF / memory parsing we instead can
just dogfood the internal Variable API to retrieve the G struct.

Backend only, no UI

Implements #120 (partial)

Fixes #198.

Instead of the `step` command single stepping every thread, instead only
step the "current" thread. This fixes a few issues surrounding single
stepping, and simplifies the logic. The original concerns around only
stepping a single thread (with regard to coordination) are invalid and
generally non-issues.

Splitting an empty string results in a one element array with a
single empty string element.

See: http://play.golang.org/p/EzVX64Q82A

Location specifiers starting with '*' can be followed by any
expression supported by the evaluator.
The expression should evaluate to either an integer (which will be
interpreted as an address) or to a function pointer (which will be
dereferenced to get the function's entry point).