fped/gnuplot.c (gnuplot_arc): implemented drawing of arcs
fped/obj.c (generate_items): handle failure to expand package name gracefully

We just use "_" in this case. Before, "expand" returned NULL, which
inst_select_pkg interprets as the global package. This in turn caused
no further packages to be defined and thus active_pkg stayed NULL.
This finally led to a crash in inst_draw.
already "fped -T" dumped, not only "fped -T -T". test/Common didn't use -T -T.
obj.c: move vector to coord translation to separate function (for future extension)
vector names can now be resolved at instantiation (partially implemented)
don't draw center cross in full-page Postscript
postscript.c (ps_for_all_pkg): "pages" was never initialized
purge unused measurement instances

Instances of measurements referencing vectors not instantiated were
only partially initialized (because only inst_meas_hint was called
on them but never inst_meas) but still left in the list of instances.

They were thus displayed, producing confusing results.

We now trace a measurement instance's validity and remove all invalid
instances at the end of instantiate_meas.
fpd.l: make start_token "static"
Makefile: generate dependencies also for YACC- and LEX-generated files

We need explicit rules to compile lex.yy.c and y.tab.c for the relaxed
CFLAGS. However, this means that the implicit rule was not used and
therefore no dependencies were generated.
change use of curly braces with "if-else" to kernel style
inst.h (FOR_PKG_INSTS): protect against active_pkg == NULL

active_pkg can become NULL if the root frame contains a loop that
will never execute, i.e., loop x = 1, 0

This caused fped to segfault when FOR_PKG_INSTS was called from
FOR_ALL_INSTS in inst_draw.
make active package track active variables (for the GUI)

If the package whose name is produced by the active variable values
is active and the variables change, then make the newly active
package the one whose name is produced by the changed variables.

This way, iterating through a table or a loop will automatically
switch to the right package, with the exception that, if the user
choses to explicitly select a different package (by clicking on
its name in the packages line), then that selection takes priority.

Explicit selection loses its priority when active package and active
variables coincide again. I.e., one can simply "catch" the active
package by activating the corresponding values.
add floor() function
test/floor: add two real-life-like rounding problems (mil to mm)
add %iprint, to track variables during instantiation
introduce keyed tables (?var syntax; WIP)

This cannot be set/changed through the GUI yet.
test/tsort: fix permission (wasn't excecutable)
gui_frame.c: display a question mark before variables used as key
support switching variables between assignment and key (WIP)

This is a little awkward: to change a variable used as key to an
assignment, one first had to change the name such that it doesn't
clash, hit Enter, and then edit the variable again to change its
type.

Variable type changes should pick up the edit in progress and allow
a type change to also imply acceptance of the variable.