This provides a better error message when the user tries to run dlv
debug on a directory that does not contain a main package, when `dlv
exec` is used with a source file.

Additionally the architecture of the executable is checked as suggested
by @alexbrainman in #443.

Fixes #509

* proc: bugfix: StepInto can not function when temp bps exist

* terminal,service: auto-continue during next and step

Make dlv call continue automatically when a breakpoint is hit on a
different goroutine during a next or step operation.
Added API hooks to implement the other solution to this problem (cancel
the next/step operation if a different breakpoint is hit).

Fixes #387

* service/api: Removed unused fields of service/api.Function

* proc/eval: Set return variable name to input expression

* all: fine-grained control of loadValue for better variable printing

Makes proc.(*Variable).loadValue loading parameters configurable
through one extra argument of type LoadConfig.
This interface is also exposed through the API so clients can control
how much of a variable delve should read.

- made GoroutineStacktrace a method of struct G
- made stacktrace a method of StackIterator
- renamed StackIterator to stackIterator
- factored out logic to obtain a stackIterator from a goroutine that's
used by both (*G).Stacktrace and by (*G).UserCurrent

It is sometimes impossible to convert an EvalScope immediately after
starting the program but disassembly can still proceed.

Automatically sets a breakpoint on runtime.startpanic, the function
that gets called by runtime.dopanic when a panic is not recovered.

Implements #317

BreakpointInfo variables were always evaluated on CurrentThread
instead of the thread that triggered the breakpoint.

Lists all the types defined in the debugged program.

proc.(*Process) methods are not thread safe, multiple clients
connecting simultaneously to a delve server (Issue #383) or a even
a single over-eager client (Issue #408) can easily crash it.
Additionally (Issue #419) calls to client.(*RPCClient).Halt can
crash the server because they can result in calling the function
debug/dwarf.(*Data).Type simultaneously in multiple threads which
will cause it to return incompletely parsed dwarf.Type values.

Fixes #408, #419 (partial)

Implements #109 and #120

Implements #368

Fixes #370.

Fixes #355

Fixes #370.

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

Fixes #360

Backend only, no UI

Implements #120 (partial)

Fixes #198.

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).

Next sets its temporary breakpoints with the condition that they
must only activate on the current goroutine, and then calls Continue
When Continue encounters a temporary breakpoint it clears all
the breakpoint.

User visible changes: breakpoints that get hit while executing Next
are not ignored.

This commit does not implement full conditional breakpoints
functionality, the only condition that can be set is on the
goroutine id.

Fixes race conditions in Next affecting TestNextConcurrent.

The new contents of api.Variable are documented in
proc/variables.go.

Implements #243

Prevents a lot of goroutines hanging around, especially when running
tests.

set <variable name> <value>

Use proc.(*Process).FindGoroutine in proc.(*Process).SwitchGoroutine and
debugger.(*Debugger).Stacktrace. That method did not exist when those
were originally written.

stack command: -full flag prints local variables and arguments of all the functions on the stack trace

Breakpoints, tracepoints, etc.. take a location spec as input. This
patch improves the expressiveness of that API. It allows:

* Breakpoint at line
* Breakpoint at function (handling package / receiver smoothing)
* Breakpoint at address
* Breakpoint at file:line
* Setting breakpoint based off regexp

Fixes #188

Allows a user to execute `dlv trace [regexp]` and Delve will execute the
program and output information on functions matching [regexp].

Fixes #95

* Cleanup comments
* Cleanup naming in certain instances
* Modify stacktrace to return current location