Fix for GitHub issue 20 : confused about signed/unsigned in strange ?: example.

The root cause was that NetESignal::dup_exr() was not copying the calculated
type (signed/unsigned) of the expression.

In passing, found and fixed a similar issue when calculating a blended value
for a constant ternary expression.
Update cppcheck suppression file.
Allow typedefs to override inherited type names.
Handle for_variable_declaration

This can be handled entirely in the parser, where we rewrite the
syntax to me a begin/end block that contains the index variable
declaration and the for loop.
Clean up pform_module_define_port in preparation for new tricks.

Get rid of the data_type, signed_flag, and range arguments to the
pform_module_define_port because they add no value within the
parse.y parser. Cleaning these out will hopefully ease the addition
of new functionality.
Symbolic printout of PortType enumeration values.
First pass at support for continuous assign of unpacked net arrays.
Handle unpacked arrays as module input ports.
Handle unpacked arrays as output ports.
Handle non-overlapping assignments to unpacked arrays.
Fix overflow calculating packed offset in certain cases.
Generalize the hname_t to handle n-dimensional scope arrays.

... Not that they actually exist yet. But this fixes some symbol
search issues and makes room for this support in the future.
Handle SEL_IDX_UP is some situations.
Fix some bugs with packed array dimensions.

The netparray_t::slice_dimensions bug was the most insidious and
caused all manner of confusion. Also fix some other packed array
and unpacked array (and mixed) indexing calculations.
Add some minor VPI/ACC fixes and updates

These were submitted.
Fix declaration of acc_fetch_paramtype
Merge branch 'x-mil13'
Merge pull request #21 from toddstrader/master

package imports in module headers