Command to step out of the currently executing function.

Implements #358

Previously Step would step through the goroutine associated with
CurrentThread if SelectedGoroutine was parked

Previously Next would step through the goroutine associated with
CurrentThread if SelectedGoroutine was parked

Also fixes a bug with proc.(*Process).StepInto where StepInto could
switch to a different goroutine.

* documentation: copied old documentation from wiki

* command: better online documentation

Help without arguments prints just a short summary for each command,
help followed by a command prints the command's syntax and a longer
explanation.

* documentation: automatically generate Documentation/cli/README.md

* 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

While tracing delve may spend most of its time outside of
proc.(*Process).Continue, which renders
service/rpc/client.(*Client).Halt ineffective.
This commit changes the implementation of
service/rpc/client.(*Client).Halt to make it capable of stopping traces.

* 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.

Issue #510

When the vars, locals, or args commands return no results, nothing is

printed out to the terminal. This commit makes these commands print a

message like `(no locals)` when there is nothing to show. This feedback

is more descriptive of what is being returned than an empty string.

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

Implements #317

Implements extensible mechanism to specify which commands accept
prefixes (goroutine, frame, on) instead of hardcoding them in
a switch.

Implements #240

Lists all the types defined in the debugged program.

Fixes #411

Implements #109 and #120

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.

Insure that the digits function always returns at least 1.

Fixes #354 (partial)

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

Fixes #360

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

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

Export the function to shorten file paths from the terminal package so
that it can be used in the `trace` subcommand.

Fixes #312

Print and set need to receive their argument unsplit to support
complex expressions

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

Implements #243

Three locations are returned for goroutines: its current location,
its current location excluding unexported runtime functions and
the location of its go instruction.
The command 'goroutines' takes a new parameter to select which
location to print (defaulting to current location w/o runtime)

This adds support for breakpoints statistics

Fixes #247

If an optional linespec argument is passed to clearall command then only
breakpoints matching this linespec will be cleared.

Behavior of clearall command without arguments hasn't changed.

The 'source' command reads the file specified as argument and executes
it as a list of delve commands.
Additionally a flag '--init' can be passed to delve specifying a file
containing a list of commands to execute on startup.

Issue #96