vsh: Add API for printing tables.

It solves problems with alignment of columns. Width of each column
is calculated by its biggest cell. Should solve unicode bug.
In future, it may be implemented in virsh, virt-admin...

This API has 5 public functions:
- vshTableNew - adds new table and defines its header
- vshTableRowAppend - appends new row (for same number of columns as in
header)
- vshTablePrintToStdout
- vshTablePrintToString
- vshTableFree

https://bugzilla.redhat.com/show_bug.cgi?id=1574624
https://bugzilla.redhat.com/show_bug.cgi?id=1584630

Signed-off-by: Simon Kobyda <skobyda@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

tools/Makefile.am

@@ -144,7 +144,9 @@ libvirt_shell_la_LIBADD = \
 		$(READLINE_LIBS) \
 		../gnulib/lib/libgnu.la \
 		$(NULL)
-libvirt_shell_la_SOURCES = vsh.c vsh.h
+libvirt_shell_la_SOURCES = \
+		vsh.c vsh.h \
+		vsh-table.c vsh-table.h
 
 virt_host_validate_SOURCES = \
 		virt-host-validate.c \