Report errors on standard error.
Use <ctype.h> instead of user-defined macros.
Reduce repetition in parser.
Ignore object files.
Refactor Makefile.

* Use 'CFLAGS' appropriately.

* Use implicit suffix rule for C files.

* Make 'shirka' depend on 'Makefile'.

* Remove 'shirka' executable on 'clean'.

* Make 'clean' phony.
Add path to 'could not open file' message.
Remove unnecessary 'NULL' comparisons.
Remove unnecessary casts on 'malloc' results.
Reduce nesting in conditionals.
Improve 'unknown escape sequence' message.
Factor duplicated character escape logic.
Add documented escapes.
Add remaining C-style escapes.
Merge pull request #2 from evincarofautumn/master

Cleanups and minor features