Eeschema: fixed some issues in undo/redo and ESC commands related to hierarchical sheets; Work in progress

fixed very minor bugs.

Build BOM: in one part per line, fields are now selectable (like others formats)

* Some bugs fixed
* Starting enhancements in Libedit: menubar and commands to "plot" current component in PNG or SVF file (SVG file not fully working, must be refined)

output 8 user fields

* Replaced find dialog with wxFormBuilder version.
* New find dialog is modeless, supports more advanced search features,
  remembers it's last position, size, search history, and search settings,
  and implements initial support for replacing.
* Added Shift+F5 hot key to search for next DRC marker.  F5 now just
  repeats previous search.
* Minor cosmetic enhancements to label edit dialog.
* Remove tab from grid size text printf to fix toolbar grid combobox
  display in wxGTK.
* Updated my TODO list items.

German translation update. Replaced dialog page settings dialogblock version by the same built with wxFormBuilder

Fixed bugs 2965646 (Canceling text operation hides text) and 2959930 (Pcbnew inconsistent Layer names sequence)

- in bloc delete, *do not delete* reference and value fields, that must always exits.
- in block copy *do not duplicate* fields that must be unique for the whole component.

default is Edit pin per pin for components with parts locked and coupling pin for others.

better use of wxString

Pad edit dialog uses now default layers names in modedit and the current board layers names in board editor

a common part being defined as have a common value.
This is true for most designs but will produce an
incorrect output if two or more parts with the same
value have different footprints, tolerances, voltage
rating, etc.  Also usefull if the following fields
are edited: 
	FIELD1 - manufacture
	FIELD2 - manufacture part number
	FIELD3 - distributor part number
Check in code for now, doc later.

(non consistent edit pin per pin option and erroneous pin number edition)
Pcbnew: fixing a problem in dialog design rules for small screens (768 pixels height); Better look on bigger screens

All: fixing a recent problem when using scroll bars: the full screen was redrawn, that can be very slow in Pcbnew.

* Make USE_WX_ZOOM clipping routine actually clip rather than just test
  if line needs drawn.
* Clean up as many USE_WX_ZOOM #ifdefs as possible.
* Minor coordinate rounding improvements.
* Minor scrolling and panning improvements.
* Remove unused KicadGraphicContext object code.

Now alias changes can be undone, and are correctly updated in lib