fill polygon with specified color

The polygon must be provided in clockwise or counter-clockwise order
(not applicable for concave polygons), as the areas need coloring will
be calculated with the order.
make fill_polygon available to client
bugfix for fill_polygon

It can now basically work.
fully fill polygon including borders
fully fill borders and vertexes in fill_polygon
fully fill polygon

In many cases, a line between two points can have more than one pixel on
the same row. Even though we have made the row_end not be drawn, it only
affects one pixel, which is the last, among the multiple pixels on each
row. All the other pixels will be drawn twice, making it disappear in
the xor map.

A new method is to make the row_start be the last of continuous series
on each row, and as row_end is also the last, none of the continuous
pixels will be drawn twice.
doc on git rules of EGUI for newbies
fix markdown in doc
Merge pull request #3 from FangYuanClaire/master

add an author
add a name into the author
name and email
add a name into authors
I add my name to AUTHORS
insert my name yanyuxi
name and email
welcome to git
bugfix in fill_polygon

When marking triangles in fill_polygon, sometimes two lines may stick
together, and the algorithm will think that they're the same line. In
this case, start and end of the row will collapse, leaving it unfilled.

Solution to this problem is to count only the last pixel of row for
every line. In the previous case, the covered area won't collapse if
only two pixels are counted (instead of two segments).
skeleton of new header for tab widget

Trying to make the tab header like the sheet selection tab in
LibreOffice Calc. Headers of all the tab pages will make up a whole
tab_header widget, which will check cursor position on mouse press and
select the tab header under cursor.

For this new widget, the button in tab_page widget is removed, and now
tab_page is a derived widget from panel. Panel is modified for being
inherited beforehand in master branch.

As the button in tab_page is removed, it is temporarily not supported to
change font for individual header of a tab page. This may be added back
by changing the page_head in tab_page widget into a label.
tab header development commit
tab header development commit

Added tab header to build system and external header files. Added a
widget testing program test_tab_header.

Clicking event is not implemented yet.