New instructions for reporting security vulnerabilities

Closes #37.
Remove unused variables
Fix object compilation target in Makefile
Merge pull request #41 from craigbarnes/makefix

Fix object compilation target in Makefile
Define HTML escape table values as uint8_t instead of char

Thanks @craigbarnes!

Closes #42.
Explicity declare the escape tables as size UINT8_MAX+1
Same for html_smartypants.c
Add Bash test runner
Fix portability issues in test runner script
Return non-zero exit code from test runner if any tests fail
Use mktemp(1) to generate temporary filenames used by the test runner
Merge pull request #44 from craigbarnes/testrunner

Shell test runner
Make test runner clean up named pipes, even on early/forced termination
Merge pull request #45 from craigbarnes/pipetrap

Make test runner clean up named pipes, even on early/forced termination
Set permissions of named pipes created by the test runner to 0600
Merge pull request #46 from craigbarnes/pipemode

Set permissions of named pipes created by the test runner to 0600
Remove execute permissions from src/html.c
Merge pull request #47 from craigbarnes/permfix

Remove execute permissions from src/html.c