- make presentation strings nicer

  four different kinds of symbols:

       a) I know exactly what this is
       b) I know in what library this is
       c) I know only the process that did this
       d) I know the name, but there is another similarly named one

  (a) is easy,  (b) should be <in ...>    (c) should just become "???" 
  (d) not sure

- grep FIXME
- make an "everything" object
       maybe not necessary -- there is a libc_ctors_something()
- consider making ProfileObject more of an object.
- hide internal stuff in ProfileDescendant
- consider caching [filename->bin_file]

DONE:

- processes with a cmdline of "" should get a [pid = %d] instead.

- Kernel module should report the file the symbol was found in

- make an "n samples" label
Process stuff:

- make threads be reported together 
  (simply report pids with similar command lines together)
  (note: it seems separating by pid is way too slow (uses too much memory),
  so it has to be like this)

- stack stash should allow different pids to refer to the same root
  (ie. there is no need to create a new tree for each pid)
   The *leaves* should contain the pid, not the root. You could even imagine
   a set of processes, each referring to a set of leaves. 

- when we see a new pid, immediately capture its mappings

Road map:
     - new object Process
       - hashable by pointer
       - contains list of maps
       - process_from_pid (pid_t pid, gboolean join_threads)
       	 - new processes are gets their maps immediately
	 - resulting pointer must be unref()ed, but it is possible it
	   just points to an existing process
	 - processes with identical cmdlines are taken together
       - method lookup_symbol()
       - method get_name()
       - ref/unref
     - StackStash stores map from process to leaves
     - Profile is called with processes

It is possible that we simply need a better concept of Process:

     If two pids have the same command line, consider them the same, period.
     This should save considerable amounts of memory.

     The assumptions: 

     	 "No pids are reused during a profiling run"
	 "Two processes with the same command line have the same mappings"

     are somewhat dubious, but probably necessary.

     (More complex kernel:

     	   have the module report
	   	
		- new pid arrived (along with mappings)
		- mapping changed for pid
		- stacktrace)

- make symbols in executable work
- the hashtables used in profile.c should not accept NULL as the key
- make callers work
- autoexpand descendant tree
- make double clicks work
- fix leaks