Minor other enhancements and code cleaning.

* EDA_DRAW_PANEL completely encapsulated.
* Moved OSX m_overlay member from EDA_DRAW_PANEL to EDA_DRAW_FRAME where
  it is used.
* Doxygen comment warning fixes.

Eeschema: fix a minor issue.

Duplicate segments where created in drag command and netlist calculations.

size while routing (W, Ctrl+W) didn't update the track in the display
window (you had to move the mouse to get a refresh).

* EDA_DRAW_FRAME completely encapsulated.
* Encapsulate the the low hanging fruit in EDA_DRAW_PANEL.

Better code in test connections in zones.
Very minor other fixes

* Add check box and flag to ignore replacing the component reference
  designator field.
* Fix a resizing bug when switching between the find and replace modes of
  the find/replace dialog.
* Fix replace component reference designator field bug.
* Force rebuild of search list when schematic is modified and the replace
  dialog is closed.
* Prevent finding the next item when the find/replace dialog is closed.
* Respect warp mouse pointer setting when closing find/replace dialog.
* Fix duplicate mnemonic control accelerator keys in find/replace dialog.

* EDA_RECT and EDA_ITEM completely encapsulated.
* Removed unnecessary EDA_ITEM member m_Selected and replaced functionality
  with SELECTED flag bit.

Removed -static-libgcc linker flag that caused Pcbnew to crash on Windows when raising an exception in release builds using MinGW GCC 4.6.1

* A track is seen connected to a pad if the track end is inside the pad shape.
* Pads inside pads are now seen connected, if the center of the pad is *inside* the other pad.
* this is made to be sure a large copper area is shared by the 2 pads,  and to keep algorithm fast.

Minor cosmetic enhancements.
Pcbnew: more workd abput connection algorithms (work in progress)

* EDA_DRAW_FRAME completely encapsulated except for DrawFrame member.
* Moved members specific to Pcbnew from EDA_DRAW_FRAME to PCB_BASE_FRAME
  or PCB_EDIT_FRAME as appropriate.
* Replace EDA_TOOLBAR with wxAuiToolBar as EDA_TOOL bar provided no
  additional functionality and made code less readable.
* Remove EDA_TOOLBAR class definition from wxstruct.h and delete file
  wineda_toolbar.cpp.
* Rename tool bar members to something more descriptive since the
  horizontal and vertical references wont mean anything once the
  tool bars are movable.
* Lots of dead code removal.

KICAD_PLUGIN::Load() is solid now, except for missing globals, which
still need to get moved into the class BOARD.

Same for KICAD_PLUGIN::Save(), only missing globals, which once they
are in the BOARD class, will be added.

Pcbnew: fix issue when creating new tracks: sometimes a ratsnest remains active although a track exists.

  * changed all the RotatePoint() functions in trigo.{h,cpp} to take a double as the
    angle, which is still in tenths of degrees for now.
  * EDA_TEXT::m_Orient is now double, still in tenths of degrees (for a short while),
    but the double means parsing files and saving them use a different format string.
++pcbnew
  * DRAWSEGMENT::GetStart() and GetEnd() do not operate for S_ARC like they used to.
    They are now simply accessors for m_Start and m_End.  Use DRAWSEGMENT::GetArcStart()
    and GetArcEnd() and GetCenter() for arcs.  specctra_export.cpp was the only
    source file dependent on the old behavior.
  * DIMENSION::m_Text is now contained, not dynamically allocated.
  * more kicad_plugin work.

* Enable replace toolbar button and menu entry.
* Improve find replace logging granularity.
* Fix find and replace dialog control hiding and disabling.
* Minor improvements to the SCH_FIND_REPLACE_DATA object.
* Move find collector list iterator into the collector object.
* Add visibility override flag to EDA_ITEM to temporarily show items that
  are hidden during find and replace.