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.

  * added BOARD::GetPad(int), made BOARD::m_NetInfo private, and contained
    within the BOARD, not dynamically allocated and owned via pointer.
  * added BOARD::GetPadCount()
  * changed NETINFO_LIST::GetCount() to GetNetCount()
  * added BOARD::GetNetCount()
  * more kicad_plugin work.

Pcbnew: fix bad initialization of default track width and vias sizes when starting pcbnew with no board loaded.

 * Fix compil issue about automatically created pcb_plot_params.h :
     pcb_plot_params.* moved from pcbnew to common because item_io.cpp (using this file) is compiled in common.

In common.cpp GetTimeStamp is renamed GetNewTimeStamp (a better name).
Pcbnew: prepare work to calculate connections between pads that inteserct and therefore can be connected without any track (composite pads).

which should eventually go away in favor of kicad_plugin.cpp.
Add CMake options USE_NEW_PCBNEW_LOAD and USE_NEW_PCBNEW_SAVE, which should not be
used yet, and both default to OFF accordingly.

and TEXTE_MODULE size in kicad_plugin.
Link in io_mgr and kicad_plugin but do not call them yet

  * Removed Pcb_Frame argument from BOARD() constructor, since it precludes
    having a BOARD being edited by more than one editor, it was a bad design.
    And this meant removing m_PcbFrame from BOARD.
  * removed BOARD::SetWindowFrame(), since BOARD::m_PcbFrame gone.
  * Removed the global BOARD_DESIGN_SETTINGS which was in class_board.cpp
  * Added BOARD_DESIGN_SETTINGS to the BOARD class, a full instance
  * A couple of dialogs now only change BOARD_DESIGN_SETTINGS when OK is pressed,
    such as dialog_mask_clearance, dialog_drc, etc.
  * Removed common/pcbcommon.cpp's int g_CurrentVersionPCB = 1 and replaced it
    with build_version.h's #define BOARD_FILE_VERSION, although there may be a
    better place for this constant.
  * Made the public functions in PARAM_CFG_ARRAY be type const.
    void SaveParam(..) const and void ReadParam(..) const
  * PARAM_CFG_BASE now has virtual destructor since we have various ways of
    destroying the derived classes and boost::ptr_vector must be told about this.
  * Pass const PARAM_CFG_ARRAY& instead of PARAM_CFG_ARRAY so that we can use
    an automatic PARAM_CFG_ARRAY which is on the stack.
  * PCB_EDIT_FRAME::GetProjectFileParameters() may no longer cache the array,
    since it has to access the current BOARD and the BOARD can change.
    Remember BOARD_DESIGN_SETTINGS are now in the BOARD.
  * Made the m_BoundingBox member private, this was a brutally hard task,
    and indicative of the lack of commitment to accessors and object oriented
    design on the part of KiCad developers.  We must do better.
    Added BOARD::GetBoundingBox, SetBoundingBox(), ComputeBoundingBox().
  * Added PCB_BASE_FRAME::GetBoardBoundingBox() which calls BOARD::ComputeBoundingBox()