Added tests for string interpolation
Added type checking for string interpolation
Add test for unsupported placeholders in string interpolation
Fixed handling of unsupported placeholders in string interpolation
Added tests for complex conversion specifiers (everything except mapping keys)
Extended string interpolation checking to accept all conversion specifier formats, except for mapping keys
Fixed handling of replacements of Any type
Fixed handling of conversion type %.
Extended checking for %c conversion type in case the replacement is a str to make sure that str is of length 1. Made checker aware of mapping keys: errors are reported when specifiers with mapping keys are mixed with those without. Error is reported when mapping keys and stars (in precision of minimum field width) are mixed. When mapping keys are present, the replacement expression is not yet checked.
Added tests for checking of key mapping in string interpolation
Added checking of key mapping in string interpolation
Small fixes
Fixed %f and %d to both accept floats and ints. Small fixes
Refactored code for creation of conversion specifier checkers
Moved all string formatter checker code into a new module
Fixed issue with double builtins in tests
Merge pull request #472 from spkersten/strinterp

Type checking of string interpolation using %