Expression format specifier support (#87)

* initial support for format specifier

* add readme notes for format specifiers

* add support for showing arrays and objects  with format specifiers

* create unique object variable references for different display formats

* add notes on applying formatting to objects and arrays

README.md

@@ -129,6 +129,39 @@ Add a new task to run the build command:
 }
 ```
 
+## Expression evaluation
+
+Format specifiers can be appended to watch and repl expressions to change how the evaluated result is displayed.
+The specifiers work with the same syntax used in Visual Studio.
+See https://docs.microsoft.com/en-us/visualstudio/debugger/format-specifiers-in-cpp for examples.
+
+```
+123              123
+123,x            0x0000007b
+123,xb           0000007b
+123,X            0x0000007B
+123,o            000000000173
+123,b            0b00000000000000000000000001111011
+123,bb           00000000000000000000000001111011
+123,c            '{'
+"one\ntwo"       "one\ntwo"
+"one\ntwo",sb    one\ntwo
+"one\ntwo",!     one
+                 two
+```
+
+You can also apply the specifiers to object and array instances to format fields and elements:
+```
+arr,x            int[3]
+   [0]           0x00000001
+   [1]           0x00000002
+   [1]           0x00000003
+```
+
+
+Note: Format specifiers for floating point values (`e`/`g`) and string encoding conversions (`s8`/`su`/`s32`) are not supported.
+
+
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