Improved stack trace output

[ezzatron]

This PR:

• Tidies up stack trace output by trimming stack entries that are irrelevant to the user.
• Adds the exception file and line number to the output, which was previously missing.
• Improves the exceptions thrown by failing assert() calls, by setting their file and line number to the location of the assert() call, rather than the location of the ASSERT_CALLBACK handler throw statement.

Closes #170.

[codecov-io]

Current coverage is 97.08% (diff: 100%)

Merging #203 into master will increase coverage by 0.13%

@@             master       #203   diff @@
==========================================
  Files            20         21     +1   
  Lines           690        721    +31   
  Methods         172        176     +4   
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits            669        700    +31   
  Misses           21         21          
  Partials          0          0          

Powered by Codecov. Last update 19c73bd...ec46daa