Merge branch 't/cleanups'

Merge branch 't/cleanups'

The changes in this branch are an attempt to make dss compile cleanly
with the more strict compiler flags (GCC 4.6 on Linux).

    -pedantic -fno-common -W -Wall -Wcast-align -Wformat=2
    -Wpointer-arith -Wundef -Waggregate-return -Wcast-qual
    -Wmissing-declarations -Wnested-externs -Wstrict-prototypes

This is only a first step that addresses the easier warnings. Some,
like the ones stemming from the variadic macros, have yet to be fixed.

	* 9e6c2f Remove some debug messages.
	* 899f88 string.c: Fix a statement-before-declaration issue.
	* 83ebb4 Remove trailing commas.
	* 2ed0d7 snap.h: Fix HSA_ITEM.
	* 508350 Fix "comma after last element" warning.
	* 97fbf4 compare_snapshots(): Add const keyword.
	* b28495 Avoid per-element initializers.
	* 9528cf dss.c: Fix initialization of argv[].
	* 4526f9 dss.c: Remove redundant const.
	* 2183c6 Makefile: Split CPPFLAGS.

Conflicts:
	error.h