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

Fixes #257

Support for dumb terminal

Fixes #252

set <variable name> <value>

Replace function with a stdlib implementation.

Default numeric argument now simply represents the depth. If you would
like to see the stack trace of another goroutine, use `goroutine <id> bt`.

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

The shortening of file paths is purely a terminal UI concern. Move that
code to the presentation layer, and remove from the service layer.