v0.4.0

* Fix memory leak in functions that use seval. ex.: dosval docat. this used to happen also in SC !
* Chain cells with equations into a new graph structure
* Change how cell expressions are evaluated
* New function to rebuilt graph
* Added free() call in GOTO in gram.y
* Added free() call in SORT in gram.y
* Added rebuild_graph, print_graph, undo and redo to gram.y
* Added function to remove elements in dep_graph. (specific vertex and linked edges)
* Fix in shift functions
* Handle circular reference with new Eval structure
* Fix in shift functions. refs in enodes now update correctly
* Undo correctly (keeping references) actions that impact in cells on which other cells depends on
* New :sum special command
* New overlap configuration parameter.
  If overlap is set to true, the cell content that exceedes column width continues to show in the following column.
* Fix a bug that prevented some info messages to be shown during loading
* Fix a bug when repaiting a cell that has a wide char size over than one.
* Changes in readfile function to fix issue that sometimes appeared
  when working with scripting, that made null output of interpreter
* Changes in sc_info sc_error and sc_debug functions..
* Changed sc_error sc_info and sc_debug functions to MACROS.
* Added new "debug" configuration parameter
* White background support
* Fix when undoing :sums that made no sums..
* :w command now adds '.sc' extension if none is specified
* Fix some #include's
* Fix :load command
* Expand filenames using wordexp
* Restored old SC fill function
* Fix in seval calls
* New :fcopy special command
* Added UNDO and LOCK check to fcopy special command. Added fcopy to gram.y
* sum special command renamed to fsum
* csv import now use isnumeric function
* change in '#' command
* new @replace string function
* Change in lex to handle WORD
* Fix in yyerror function
* :set command improvement
* Added set to gram.y
* doc improvement
* Fix when opening files with slash