Library section improvement for .sch file

[Alexey Kharikovskiy]

Patched gschem will be create "library section" in .sch file. In this section will be placed symbols, which are used in it.
   After .sch file was opened, missing symbols will be placed in "library section" from standart library or local lybrary, included in gafrc.
   After add component ("i"), if adding symbol (that is content of one) are absent in "library section" of .sch file, it will be added.
   If name of adding symbol is exist in "library section, but content of symbol differs, symbol will be added with another name.
For example:
In "library section" exists symbol "opamp-dual.sym" with Content1.
I add symbol "opamp-dual.sym" by "i" and it have Content2 != Content1.
At result symbol "opamp-dual.sym0" was added to "library section" with Content2.
Next names will be "opamp-dual.sym1" and so on by increment.

More with example of similar schematic file
http://comments.gmane.org/gmane.comp.cad.geda.user/42830

[Alexey Kharikovskiy (svetonomer)]

Example of schematic file with library section

[Alexey Kharikovskiy (svetonomer)]

I wrote lib_sec_utils.py script to work with the Library section.

In attached archive the lib_sec_utils.py scripts and tests to it.