Fix missing empty, clear and size methods for strings

Fixes bugs #95 and #93
Add unit tests for string size() fixes #93 #95
Merge branch 'master' into ChaiScript_5_0_CPP_11
Add module search path relative to current exe #94
Merge branch 'master' into ChaiScript_5_0_CPP_11

Fix for issue #94

Conflicts:
	src/main.cpp
Fix (legit) warning in VisualStudio
fix building main.cpp when readline is available

This changes around the pragma conditionals to make sure that certain
symbols (such as "default_search_path") are defined even if the system
has readline available during builds.
Merge pull request #96 from kanzure/fix-readline-build

Make main.cpp compile when readline is available
force no unicode in search parth windows