added KNOWN_ISSUES file. fix bug when trying to read null variables in history.c.
some cleaning
Delete .string.c.swp
Update Makefile

Add install rule, remove all the custom per-file rules.
Makefile bugfix: Respect PREFIX in 'make install'
Merge pull request #9 from trozamon/make

Makefile fixes - Many thanks trozamon!!
fix in file permissions
Makefile bugfix + add uninstall rule
Merge pull request #10 from trozamon/make

Makefile bugfix + add uninstall rule
add comment in undo.c and fix revision number in Makefile. delete exec.h file not used.
csv and tab delimited export (experimental)
hide and show rows and cols with Zc, Zr, Sc and Sr commands.
added 'Import CSV' to TODO file
some cleaning and fixes
Clean in hide_show.c
Implemented UNDO and REDO of Zr Zc Sr Sc commands
mods in help.
search hotkey in help page. "/ hotkey".