Handle a float that does not occur after a numeric string

[Wolfe-Lyon]

In some cases, a floating point number in a basic program may occur after a non-numeric character. For example the basic loader for Trap Door contains the following sequence of bytes:

0,0,70,0,253,50,52,53,55,53,32,8,14,143,71,52,51,51...

The LIST command (and snapinfo.py prior to the current change) will show this as:

0 CLEAR 24575 {0x08}...

However the true program as processed by the basic interpreter is:

0 CLEAR 25498.1...

The changes in this pull request should enable snapinfo.py to display the hidden floating point number.

Changes:

• If a float is present and does not follow immediately after a numeric string, it will always be printed. The existing behaviour, whereby a float may or may not be printed depending upon whether or not it agrees with the numeric string when it follows immediately after such has been preserved.
• A new unit test (test_floating_point_number_after_non_number) has been added to test the new functionality.
• The existing unit test test_all_tokens has been modified to remove a "hidden" floating point number that was present in line 290.

[codecov-io]

Codecov Report

Merging #99 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #99   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          35     35           
  Lines        9741   9743    +2     
=====================================
+ Hits         9741   9743    +2

Impacted Files	Coverage Δ
skoolkit/basic.py	100% <100%> (ø)	⬆️

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[skoolkid]

Well spotted! However, there are a couple of problems with this patch:

• It shows the value of the floating point number even when it matches the numeric string that is followed by spaces and non-printable characters (e.g. '10 PRINT 1 {0x08}{1}')
• It shows the value of the floating point number placeholders in DEF FN statements

I've committed a fix in 014414d. It also fixes another bug I noticed while in that area of code: if a fake floating point number was zero, its value was not being shown.