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).

Temp breakpoints should be cleared even if a non-temp breakpoint is
triggered on the same goroutine that the temp breakpoints are set on.

Fixes #305

Prefetch the entire memory of structs and arrays and cache it instead
of issuing readMemory calls only when we get down to primitive types.
This reduces the number of system calls to ptrace that variables makes.

Improves performance in general, greatly improving it in some
particular cases (involving large structs).

Benchmarks without prefetching:
	BenchmarkArray-4         	      10	 132189944 ns/op	   0.06 MB/s
	BenchmarkArrayPointer-4  	       5	 202538503 ns/op	   0.04 MB/s
	BenchmarkMap-4           	     500	   3804336 ns/op	   0.27 MB/s
	BenchmarkGoroutinesInfo-4	      10	 126397104 ns/op
	BenchmarkLocalVariables-4	     500	   2494846 ns/op

Benchmarks with prefetching:
	BenchmarkArray-4         	     200	  10719087 ns/op	   0.76 MB/s
	BenchmarkArrayPointer-4  	     100	  11931326 ns/op	   0.73 MB/s
	BenchmarkMap-4           	    1000	   1466479 ns/op	   0.70 MB/s
	BenchmarkGoroutinesInfo-4	      10	 103407004 ns/op
	BenchmarkLocalVariables-4	    1000	   1530395 ns/op

Improvement factors:
	BenchmarkArray				12.33x
	BenchmarkArrayPointer		16.97x
	BenchmarkMap					 2.59x
	BenchmarkGoroutinesInfo		 1.22x
	BenchmarkLocalVariables		 1.63x

Fixes #341

recurseLevel value should not be reset when evaluating the contents
of an interface variable

Fixes #316

The concrete type of an interface only contains the abbreviated
package name, we must construct a map from package names to package
paths to be able to resolve the concrete type of an interface.

It's was implemented unintentionally and the unintentional
implementation doesn't work and causes a crash.

Fixes #288

Use m[n:] to skip the first n keys of a map
Map indexing is implemented with a linear scan

Implements #61, #122

Pretty print will print them with the format:
chan <element type> <queued elements>/<queue size>

Supported operators:

- All (binary and unary) operators between basic types except <-,
++ and -- (includes & to take the address of an expression)
- Comparison operators between supported compound types
- Typecast of integer constants into pointer types
- struct members
- indexing of arrays, slices and strings
- slicing of arrays, slices and strings
- pointer dereferencing
- true, false and nil constants

Implements #116, #117 and #251

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)

Embedded structs are encoded in DWARF as fields with
package-qualified names.  They define an anonymous field
on the struct with the non-qualified name, as well as
promoted fields for each field of the embedded struct so
long as these are not shadowed by fields of the containing
struct.

Fixes #220.

g.SP refers to the frame the goroutine was in the last time it was
scheduled out. Instead of calling proc.(*Process).stacktrace directly
we should call proc.(*Process).GoroutineStacktrace that substitutes
fresh values retrieved from thread registers when necessary.
This bug leads to occasional problems with `next`.

Fixes #220

set <variable name> <value>

Refactored variables.go to separate calculation of a variable's address from
reading its value. This change is useful to implement the 'set' command
as well as the evaluation of more complex expressions (in the future).

Be more tolerant of unitialized memory, limit length of strings like we
do for array/slices.

Workaround for Issue #189

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

Some of the goroutines stored in runtime.allg are in the dead state and
should not be displayed. The state is determined by the 'g.atomicstatus'
member.

gopc is the instruction of the `go` command that spawned this goroutine.
What we really want (unless we can get the PC from the thread) is the
value of sched.pc which is the value of the PC at the time it was
parked.

This fix helps avoid infinite recursion.

Fixes #192